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33403 Publications

The role of flash lamp annealing for the recrystallization of ion implanted ZnO

Prucnal, S.; Braun, M.; Wang, M.; Liu, F.; Snigurenko, D.; Berencen, Y.; Guziewicz, E.; Rebohle, L.; Zhou, S.; Skorupa, W.
A highly doped n-type ZnO thin layer is an attractive candidate to replace the much more expensive indium-tin-oxide layer in photovoltaics and low cost electronics. The optoelectronic properties of ZnO are determined by the type of doping and carrier concentration. The n-type conductivity of ZnO is easily achieved by substitution of Zn through the group III elements (Al, Ga, In), or by doping with halogen elements (F, Cl or I) substituting into the oxygen lattice site. However, the effective p-type doping of ZnO remains challenging. The most promising p-type dopants in ZnO are group V elements. In this paper, we have investigated the influence of millisecond range flash lamp annealing (FLA) on the recrystallization mechanism and optoelectronic properties of ion implanted ZnO thin films. The 120 nm thick ZnO films were grown on Si substrates by atomic layer deposition and implanted with P and Sb ions. After ion implantation FLA was used to anneal defects created during the ion implantation process and to activate finally the dopants. Samples were annealed for 3 or 20 ms using oxygen-poor (N2 or Ar) and pure oxygen atmosphere. The influence of the annealing conditions (atmosphere, annealing time and flash energy) on the optical and electrical properties of implanted ZnO was investigated using temperature dependent photoluminescence, Raman spectroscopy and Hall Effect measurements. The microstructural properties of fabricated ZnO films were studied using cross-section TEM and X-ray diffraction spectroscopy. It will be demonstrated that via millisecond range FLA treatment not only the implanted ions can be efficiently incorporated into the lattice of ZnO but also defect engineering is possible. By a proper selection of the implanted species and annealing atmosphere the main optical emission observed from doped ZnO can be easily changed from the UV to the red. This allows the fabrication of spectrally-clean blue, green and red emitters. According to Hall Effect and PL measurements the annealing atmosphere during FLA is crucial for the realization of p-type ZnO layers. The oxygen-poor atmosphere promotes the Zn-interstitial formation enhancing the n-type conductivity of ZnO. Annealing in oxygen suppresses the formation of n-type defects and stabilizes the p-type conductivity of ZnO films. This work has been partially supported by the EU 7th Framework Programme (EAgLE) (REGPOT-CT-2013-316014).
Keywords: ZnO, doping, flash lamp annealing, photoluminescence
  • Poster
    E-MRS 2016 Fall Meeting, 19.-22.09.2016, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-24681
Publ.-Id: 24681


Complex electronic structure of Zni and Oi defects in ZnO

Prucnal, S.; Wang, M.; Liu, F.; Wu, J.; Cai, H.; Zhou, S.; Skorupa, W.
To these days ZnO is one of the most widely investigated types of transparent conductive oxides except ITO. The electronic structure of most of the native defects in ZnO was studied both theoretically and experimentally using various methods. Based on simulation and experimental results, A. Sokol, et al., , have proposed a complex model for the electronic structure of different point defects in doped and undoped ZnO [Faraday Discuss., 134, 267-282 (2007)]. There is agreement that the zinc interstitial (Zni) is a shallow donor and is mainly responsible for the n-type conductivity of intrinsic ZnO. The oxygen interstitial (Oi) is neutral in ZnO, has the energy level located about 2.8 eV below the bottom of the conduction band, and is mainly responsible for the blue-green emission at 2.5 – 2.3 eV. But the energy levels of exited Zni* and Oi are controversial. Using density functional theory calculations, Yong-Sung Kim and C. H. Park have shown that Zni* should have an energy level above the conduction band but to this day it has not been proven experimentally and the exact energy position is unknown [Phys. Rev. Lett. 102, 086403 (2009)]. In order to verify their theory we have performed detailed optical and electrical investigations of ZnO films deposited on insulating Si wafers by reactive pulsed laser deposition. The defect engineering in ZnO was performed using non-equilibrium flash lamp annealing operated in the millisecond range with different annealing ambient. Temperature dependent photoluminescence (PL) emission and excitation (PLE) were utilised to determine the radiative transitions and excitation levels in ZnO, respectively. In order to determine the carrier concentration and conductivity type of processed ZnO films, Hall Effect measurements were performed in the temperature range from 3 to 300K. According to PLE the first excited levels of Zni* and Oi are located at 0.83 eV and 0.70 eV above the conduction band, respectively. The concentration of Zni* and Oi is determined by the annealing atmosphere. The oxygen-poor atmosphere promotes the Zn-interstitial formation while annealing in oxygen suppresses the n-type defects and increases the Oi concentration. Comparison of temperature dependent PL and Hall Effect data confirms that the Zni is a main intrinsic source of n-type conduction in ZnO.
Keywords: ZnO, defect engineering, flash lamp annealing, photoluminescence
  • Poster
    E-MRS 2016 Fall Meeting, 19.-22.09.2016, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-24680
Publ.-Id: 24680


Atomic layer deposition of nitrogen-doped titanium dioxide films

Luka, G.; Wierzbicka, A.; Guziewicz, E.; Prucnal, S.; Skorupa, W.
Layers and nanostructures of titanium dioxide (TiO2) have found several practical applications for paints, sunscreens, protecting layers, photocatalysis, water splitting or photovoltaics. The applicability of this material depends on its crystalline phase. Among the three possible crystal structures of TiO2, anatase is commonly used for photocatalysis. TiO2 with anatase structure, however, can undergo transition to the rutile phase, which is accelerated by the heat treatment at temperatures between 450 and 1200 °C. In our work, we obtained undoped and nitrogen-doped titanium dioxide (TiO2:N) films, grown by atomic layer deposition, with a stable anatase structure. The as-grown amorphous films were deposited at 120 °C on single crystalline Si substrates. After deposition samples were annealed by flash lamp annealing for 20 ms in nitrogen ambient. Annealed films show anatase structure which is stable up to anneal temperatures close to the melting point of Si (< 1400 °C). This was confirmed by ?-Raman and x-ray diffraction studies. We analyze the anatase crystal structure of the annealed TiO2:N films as a function of the annealing energy density and the N concentration. The investigations are complemented by temperature-dependent photoluminescence measurements. The work was partially supported by the EU 7th Framework Programme project REGPOT-CT-2013-316014 (EAgLE).
Keywords: TiO2, photoluminescence, flash lamp annealing
  • Lecture (Conference)
    E-MRS 2016 Fall Meeting, 19.-22.09.2016, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-24679
Publ.-Id: 24679


RBS/c and PL studies of ZnO implanted with Pr ions

Ratajczak, R.; Prucnal, S.; Mieszczynski, C.; Guziewicz, E.; Stachowicz, M.; Snigurenko, D.; Kopalko, K.; Witkowski, B. S.; Krajewski, T. A.; Turos, A.
High-quality ZnO epitaxial layers deposited by Atomic Layer Deposition were implanted at room temperature with 150 keV Pr3+ions to fluence of 1x1015 and 2x1015. Two different types of annealing on as implanted samples were performed: rapid thermal annealing (RTA) and flash lamp annealing (FLA). Crystalline quality, damage recovery and Yb lattice site location were evaluated by the Channeling Rutherford Backscattering Spectrometry (RBS/c). The optical properties were studied by photoluminescence (PL). Upon annealing defects recovery has been observed. After RTA the return of Zn atoms to their substitutional sites produces displacement RE atoms into interstitial positions. The increase of RTA temperature and time leads to enhanced out-diffusion of RE atoms. Consequently, better recovery of the crystal structure is accompanied by lower photoluminescence (PL) efficiency. The FLA precludes the RE-atom surface segregation. The substitutional fraction of Pr ions is higher than after RTA with the same structure recovery, but PL intensity from Pr3+ is lower. This suggests that the substitutional RE atoms are preferentially in the 2+ state. Acknowledgments: The work was supported by the NCBiR (Poland) project PBS2/A5/34/2013 and by the EU 7th FP project REGPOT-CT-2013-316014 (EAgLE), by the Polish Ministry of Science and Higher Education (3418/SPIRIT/2015/0) and by the Helmholtz Zentrum Dresden-Rossendorf (HZDR) in a frame of the program Access to Infrastructure (15100222-ST and 16000696-ST).
Keywords: ZnO, Rare Earths, ion implantation, flash lamp annealing, photoluminescence
  • Poster
    E-MRS 2016 Fall Meeting, 19.-22.09.2016, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-24678
Publ.-Id: 24678


Fabrication and studies of short period ZnO/MgO superlattices

Kozanecki, A.; Pietrzyk, M.; Stachowicz, M.; Prucnal, S.; Skorupa, W.; Dyczewski, J.; Dluzewski, P.
In this work we present the optical and structural characteristics of ZnO/MgO short period superlattices grown on c-plane ZnO. The structures were composed on 80 pairs of ZnO/MgO thin layers. Rutherford backscattering allowed to estimate the real thickness of the structures and compare them with the intended one. The thicknesses differed from growth to growth and they were on the order of 1 nm ZnO to 1-1.5 nm MgO. The thickness of MgO layers was crucial for the growth mode and resulting quality of the structures. Channeling measurement revealed that in the case of the thinnest MgO layers the growth of superlattices was coherent, as χmin of the backscattering yield for the superlattice is the same as for ZnO substrate. This very good crystalline quality was also reflected in photoluminescence (PL) measurements, which revealed PL typical of superlattice. However, the PL of some structures showed that ZnMgO alloy was formed instead of the superlattice. PL excitation spectra allowed to determine the band gap values of the ZnO/MgO structures by observation of the PL from the ZnO substrate. Reasons for it are discussed. Transmission Electron Microscope imaging allows to compare both types of structures. Acknowledgements. The work was supported by the NCN project DEC-2014/15/B/ST3/04105 and by the EU 7th FP project REGPOT-CT-2013-316014 (EAgLE).
Keywords: ZnO, ZnO/MgO, photoluminescence, superlattice
  • Poster
    E-MRS 2016 Fall Meeting, 19.-22.09.2016, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-24677
Publ.-Id: 24677


Hot electron engineering for boosting electroluminescence efficiencies of silicon-rich nitride light emitting devices

Berencén, Y.; Mundet, B.; Rodríguez, J. A.; Montserrat, J.; Domínguez, C.; Garrido, B.
The combination of a SiO2 electron accelerator layer with a silicon-rich nitride layer forming a bilayer embedded in a metal-oxide-semiconductor structure has proved to enhance the integrated visible-infrared EL intensity by more than two orders of magnitude in comparison to the single-layer electroluminescent device approach. The origin of such an improvement is attributed to the massive ionization of defects in the silicon-rich nitride layer by direct impact of injected hot electrons coming from the SiO2 conduction band. Our premises are further corroborated by performing a thorough study of the charge transport in the bilayer structure. This study displays a main electrical mechanism at steady state that combines hot-electron tunneling injection from the SiO2 accelerator layer and space charge-limited current enhanced by Poole-Frenkel conduction from the silicon-rich nitride electroluminescent layer. The proposed electrical mechanism is validated by numerical simulations that provide good agreement with the experimental behavior. These results point out the feasibility of boosting electroluminescence efficiency of Si-based light emitting devices by performing an adequate gate stack engineering that maximizes the hot-electron injection into the electroluminescent layer.
Keywords: Hot electron engineering; Silicon-rich nitride; Electrical transport; Electroluminescent devices

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Permalink: https://www.hzdr.de/publications/Publ-24676
Publ.-Id: 24676


Non equilibrium thermal processing of highly implanted ZnO:Yb

Stachowicz, M.; Ratajczak, R.; Prucnal, S.; Skorupa, W.; Krajewski, T. A.; Witkowski, B. S.; Snigurenko, D.; Turos, A.; Guziewicz, E.
ZnO epitaxial layers deposited by Atomic Layer Deposition were implanted with Yb ions to a fluence of 1x1016 at./cm2 at energy of 150 keV. Different types of annealing (in oxygen or ambient atmosphere) of ZnO:Yb samples have been performed: millisecond range flash lamp annealing (FLA), rapid thermal annealing (RTA) up to 30 min. and tube furnace annealing (TFA) up to 1 h at 800oC. It was found that the optical properties of ZnO:Yb films are strongly affected by the annealing time. According to Rutherford Backscattering and channeling (RBS/c) the annealing of implanted films leads to a partial recovery of the crystal lattice. The photoluminescence (PL) spectra in combination with RBS/c reveal that the worse reconstruction of lattice and reduction of the fraction of substitutional Yb ions results in more intense emission around 0.98 µm in case of RTA and TFA annealing. Surprisingly, the FLA annealing has shown very good result in terms of PL intensity at RT as a thermal quenching effect is much weaker in this case. The RBS/c and PL results lead to a conclusion that RTA and FTA annealing promotes cluster formation and outdiffusion of Yb while FLA suppresses it. Acknowledgements. The work was supported by the NCBiR (Poland) through the project PBS2/A5/34/2013 and by the EU 7th FP project REGPOT-CT-2013-316014 (EAgLE). It was also co-financed by Helmholtz Zentrum Dresden-Rossendorf (HZDR) in the frame of the program Access to Infrastructure (15100222-ST).
Keywords: ZnO, Yb, ion implantation, photoluminescence
  • Poster
    E-MRS 2016 Fall Meeting, 19.-22.09.2016, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-24675
Publ.-Id: 24675


Ge comeback - new properties of an old material

Prucnal, S.
One of the main obstacles towards wide application of Ge in nanoelectronics is the lack of an efficient doping method for the fabrication of heavily doped Ge layers with well controlled junction depth. In fact, n-type doping of Ge is a key bottleneck in the realization of advanced negative-channel metal-oxide-semiconductor (NMOS) devices. Here we use ion implantation followed by flash-lamp (FLA) annealing for the fabrication of heavily doped Ge with comparably high mobility. In contrast to conventional annealing procedures, rear-side FLA leads to full recrystallization of Ge and dopant activation independently of pre-treatment. The maximum carrier concentration is well above 1020 cm-3 for n-type and above 1021 for p-type doping. The recrystallization mechanism and the dopant distribution during rear-side FLA are discussed in detail.
In this work, we report on the strong mid-IR plasmon absorption from heavily P-doped Ge thin films and superconductivity in Ga implanted Ge obtained by non-equilibrium thermal processing. Ultra-doped Ge layers were fabricated by ion implantation of P or Ga ions followed by rear-side flash lamp annealing in the millisecond range. This approach, in contrast to conventional annealing procedures, leads to full recrystallization of Ge films and high dopant activation. In this way single crystalline Ge thin films free of defects were obtained. The mid-IR plasmon spectral response at room temperature from those samples was characterized by means of Fourier transform infrared spectroscopy. It is proven that the position of the plasmonic resonance frequency signal can be tuned as a function of the P concentration.
Keywords: Ge, n-type doping, plasmonics, FLA
  • Invited lecture (Conferences)
    International Conference Ion Implantation and other Applications of Ions and Electrons, 13.-16.06.2016, Kazimierz Dolny, Poland

Permalink: https://www.hzdr.de/publications/Publ-24674
Publ.-Id: 24674


Room-temperature sub-band gap photoresponse from Se-hyperdoped Si p-n photodiodes

Berencén, Y.; Liu, F.; Wang, M.; Zhou, S.; Rebohle, L.; Helm, M.; Skorupa, W.; Prucnal, S.
The development of room-temperature short-wavelength infrared Si photodetectors is of paramount importance for optical communications, integrated photonics, sensing and medical imaging applications [1]. The typical peak photoresponse of conventional Si photodetectors is between 700 and 900 nm, which is mainly limited by the 1.12 eV-Si indirect band gap. Nevertheless, such intrinsic material limitation can be circumvented by introducing transition metals or chalcogens into the Si band gap at concentrations far above those obtained at equilibrium conditions [1, 2]. This new class of hyperdoped materials with a donor impurity band has been postulated as a viable route to extend the Si photoresponse at the short-wavelength infrared spectral region [3]. In this work, we report on the significant room-temperature photoresponse and performance at wavelengths as long as 3100 nm as exhibited by hyperdoped Si p-n photodiodes fabricated by Se implantation followed by flash lamp annealing (FLA). The FLA approach in the millisecond range allows for a solid-phase epitaxy that has been reported to be superior to liquid-phase epitaxy induced during pulsed laser annealing [2]. The success of our devices is primarily based on the high quality of the developed n-type hyperdoped material, which is single-phase single crystal with high electrical activation, without surface segregation of Se atoms and with an optically flat surface. [1] J. P. Mailoa, A. J. Akey, C. B. Simmons, D. Hutchinson, J. Mathews, J. T. Sullivan, D. Recht, M. T. Winkler, J. S. Williams, J. M. Warrender, P. D. Persans, M. J. Aziz, and T. Buonassisi, Nat. Commun. 5, 3011 (2014). [2] S. Zhou, F. Liu, S. Prucnal, K. Gao, M. Khalid, C. Baehtz, M. Posselt, W. Skorupa, and M. Helm, Sci. Rep. 5, 8329 (2015). [3] I. Umezu, J. M. Warrender, S. Charnvanichborikarn, A. Kohno, J. S. Williams, M. Tabbal, D. G. Papazoglou, X. C.Zhang, and M. J. Aziz, J. Appl. Phys. 113, 213501 (2013)
Keywords: Si, hyperdoping, FLA, Se, ion implantation
  • Lecture (Conference)
    E-MRS 2016 Fall Meeting, 19.-22.09.2016, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-24673
Publ.-Id: 24673


Optoelectronic properties of ultra-doped Ge fabricated by ion implantation and flash lamp annealing

Prucnal, S.; Berencén, Y.; Heera, V.; Voelskow, M.; Yuan, Y.; Wang, M.; Poddar, V.; Mazur, G. P.; Grzybowski, M.; Zgirski, M.; Sawicki, M.; Hübner, R.; Zhou, S.; Skorupa, W.
Independent of the type of doping, it is challenging to achieve in semiconductors an effective carrier concentration much above 10^20 /cm3. On the other hand, the successful realization of defect free n-type and p-type ultra-doped Ge layers will enable a range of devices from sensors to quantum computers. In the case of conventional doping techniques (using equilibrium processing) the maximum carrier concentration is limited by the out-diffusion of dopants, a relatively low solid solubility limit, clustering and self-compensation processes. To overcome such limitations we have utilised strong nonequilibrium process consisting of an ion beam implantation to introduce dopants into Ge and rear-side millisecond range flash lamp annealing (FLA) for recrystallization of implanted layer and dopant activation. In contrast to conventional annealing procedures, rear-side FLA leads to full recrystallization of Ge and dopant activation independent of the pre-treatment. The maximum carrier concentration is well above 10^20 /cm3 for n-type and above 10^21 /cm3 for p-type dopants. The so-fabricated n-type Ge can be used in the field of mid-infrared plasmonics which has not been accessible by group-IV semiconductors. Single crystalline n-type Ge with carrier concentrations as high as 2.2×10^20 /cm3 displays a room-temperature plasma frequency above 1850 /cm1 (?=5.4 ?m), which is the highest value ever reported for n-type Ge. In the case of Ga implanted Ge the maximum effective carrier concentration measured at 3K is 1.1×10^21 /cm3 which is two times higher than the solid solubility limit of Ga in Ge. Our p-type Ge is defect and cluster free and shows the superconductivity at Tc = 0.95 K. These results base on the successful combination of ion beam implantation followed by the novel approach consisting of millisecond range rear-FLA. This work has been partially supported by the EU 7th Framework Programme "EAgLE" (REGPOT-CT-2013-316014).
Keywords: Ge, n-type, ion implantation, FLA
  • Lecture (Conference)
    E-MRS 2016 Fall Meeting, 19.-22.09.2016, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-24672
Publ.-Id: 24672


In Situ Study of Metal Induced Crystallization Processes for Low-Dimensional Materials Synthesis

Wenisch, R.; Janke, D.; Heras, I.; Heller, R.; Hanf, D.; Hübner, R.; Munnik, F.; Gemming, S.; Krause, M.
Metal induced crystallization (MIC) is a promising technique for low-temperature thin film transistor fabrication and graphene synthesis. In MIC, a transition metal catalyzes the crystallization of the amorphous phase of a group IV element by bond screening near the interface and facilitation of nucleation. So far, in situ studies have been performed using X-ray diffraction, which is sensitive to the degree of crystallinity. In situ Rutherford backscattering spectrometry has the advantage of elemental depth resolution and time resolved tracking of diffusion and layer exchange processes. Graphene formation through MIC has been demonstrated with an a-C/Ni layer stack [1].
As a model system for MIC, the Si/Ag bilayer system is studied here. The Si/Ag layer stacks are annealed at temperatures of 380 to 700 °C. Depth profiles of the elements are investigated by in situ RBS. Their analysis reveals the diffusion kinetics of the elements. The changes in the phase structure are explored by in situ Raman spectroscopy. Both the quick initial nucleation and ensuing growth processes are investigated.
[1] Weatherup et al., Nano Letters 13, pp. 4624 (2013)
Keywords: Metal induced crystallization In situ Raman In situ RBS
  • Poster
    International Winterschool on Electronic Properties of Novel Materials 2016, 13.-20.02.2016, Kirchberg in Tirol, Österreich

Permalink: https://www.hzdr.de/publications/Publ-24671
Publ.-Id: 24671


Effect of microstructure on the magnetic properties of transition metal implanted TiO2 films

Yildirim, O.; Cornelius, S.; Butterling, M.; Anwand, W.; Wagner, A.; Smekhova, A.; Huebner, R.; Boettger, R.; Fiedler, J.; Baehtz, C.; Potzger, K.
The origin of the ferromagnetic order in TM:TiO2 (TM: transition metal) systems is studied by investigating the interplay between structural order, defects and incorporation of implanted TM ions within the host lattice. The defect properties of the host TiO2 films are altered by preparing different microstructures of TiO2 (e.g. amorphous, polycrystalline anatase and epitaxial anatase). The difference in microstructure is also found to influence the incorporation of the implanted ions into the host lattice. The crystallographic incorporation of the implanted TM atom is found only in crystalline films. Moreover, it is observed that the suppression of the dopant related secondary phases can also be achieved by changing the microstructure. Based on this discussion we propose an ideal microstructural candidate for a dilute magnetic oxide material based on our results.
  • Poster
    80. DPG-Jahrestagung und DPG-Frühjahrstagung der Sektion Kondensierte Materie, 06.-11.03.2016, Regensburg, Germany

Permalink: https://www.hzdr.de/publications/Publ-24670
Publ.-Id: 24670


Long-range focal series reconstruction in the TEM

Lubk, A.; Vogel, K.; Wolf, D.; Röder, F.; Clark, L.; Verbeeck, J.
Focal series wave reconstruction in the Transmission Electron Microscope (TEM) is a well established holographic technique employed in both the medium and atomic resolution regime to study electric, magnetic and strain fields in solids as well as atomic configurations at crystal defects or grain boundaries. Focal series reconstruction does not require an undisturbed reference wave as off-axis holography and may be conducted under relaxed partial coherence provided that the latter is well-behaved and well-known in advance [1]. Moreover, focal series holography may be considered as an instance of the more general quantum state tomography (see Fig. 1) that is successfully employed to study mixed (i.e., incoherent) quantum states of matter (e.g., atoms) and light [2].
These advantages are opposed by ambiguities in the reconstructed wave function, e.g., due to inconsistent and incomplete focal series data. In reality every focal series is inconsistent, e.g., due to the presence of partial coherence, shot and detector noise, as well as geometric and chromatic aberrations depending on the defocus. Similarly, every focal series is incomplete because of a limited number of foci, typically limited to the near field regime, and the restriction to isotropic foci, where astigmatic foci are necessary to provide a dataset allowing for an unabiguous reconstruction of an underlying wave function [3]. For instance, the problematic reconstruction of low spatial frequencies can be traced back to missing focal series data in the far field.
Here, we elaborate on focal series reconstruction from the perspective of quantum state tomography and use the obtained results to increase the scope of the technique in terms of convergence and uniqueness in particular for low spatial frequencies. Moreover, we explain a number of previous results by exploiting the above analogy, and open pathways to further improvements.
We particularly report on the recording, preprocessing, calibration and reconstruction of a long range focal series ranging from the near to the far field in a TEM. We calibrate the focal series, including the effective defocus and magnification, by a careful calibration of the proportionality between squared current and reziprocal focal length in a magnetic lens. We derive non-linear focal sampling schemes from the phase space analogy. Subsequently, we adapt a modified Gerchberg-Saxton algorithm to the long range focal series by exploiting the link to randomized Kaczmarz (ART) algorithm used in tomography [4]. We use different numerical propagation regimes in the near and far field to take into account the scaling of the wave function and overcome convergence problems by replacing the Kaczmarz iteration with the Landweber (SIRT) iteration as proposed by Allen et al.. [5]. To overcome remaining ambiguities in the reconstruction (e.g, pertaining to a different starting guess in the Gerchberg-Saxton algorithm) resulting from inconsistencies in combination with the non-convex nature of the set of wave functions possessing the same modulus, we discuss several additional constraints such imposed by the topology of the starting guess [6].
To illustrate the above reconstruction principles, we perform a case study on a higher-order vortex beam with topological charge (winding number) 3 truncated by a square aperture (Fig. 2). The beam possesses a non-trivial topology by design, which is nicely suited to discuss the impact of (implicit) topology constraints, rotation alignment as well as other issues.

[1] Koch, C. T., Micron, 2014, 63, 69-75
[2] Schleich, W. P., Quantum Optics in Phase Space, Wiley VCH, 2001
[3] Lubk, A. & Röder, F., Phys. Rev. A, 2015, 92, 033844
[4] Natterer, F., Wübbeling, F., Mathematical Methods in Image Reconstruction,SIAM, 2001
[5] Allen, L. J.; McBride, W.; O’Leary, N. L.,Oxley, M. P., Ultramicroscopy, 2004, 100, 91-104
[6] Martin, A. & Allen, L., Optics Communications, 2007, 277, 288-294
[7] Financial support by the DIP programme of the DFG is greatly acknowledged.
  • Lecture (Conference)
    16th European Microscopy Congress, EMC 2016, 28.08.-02.09.2016, Lyon, Lyon

Permalink: https://www.hzdr.de/publications/Publ-24669
Publ.-Id: 24669


Electron interferometry techniques for strain analysis using a multibiprism microscope

Denneulin, T.; Röder, F.; Houdellier, F.; Gatel, C.; Snoeck, E.; Hÿtch, M. J.
Electron interferometric techniques have progressed in the last years thanks to the development of multiple biprisms microscopes. Here, we will discuss some recent developments in the field of strain measurement carried out with the I2TEM microscope (In-situ Interferometry Transmission Electron Microscope) installed in Toulouse in 2012. The I2TEM is a Hitachi HF-3300 equipped with one pre-specimen electrostatic biprism, three post-specimen biprisms, an image corrector (CEOS B-COR for correcting off-axial aberrations) and two stages (objective stage and Lorentz stage above the objective lens). In the dark-field off-axis scheme [1], electron beams diffracted by an epitaxially grown region are interfered with beams diffracted by the substrate thanks to a post-specimen biprism (Fig. 1(a)). Fig. 1(b-d) is an example obtained on a p-MOSFET like transistor with SiGe source/drain. The deformation is recorded as a frequency modulation (FM) in the hologram (Fig. 1(c)) and it can be calculated from the gradient of the reconstructed phase image (Fig 1(d)). In a recently proposed variant called differential phase contrast dark-field holography (DPCDFEH) [2], a pre-specimen biprism is used to create two overlapping waves on the sample (Fig. 1(e)). The interference of beams diffracted by slightly distant regions is acquired in a defocused plane. The deformation is recorded as a phase modulation (PM) in the hologram (Fig. 1(f)) and the DPC phase is directly proportional to the deformation (Fig. 1(g)). Another option is the 4-wave dark-field setup where two biprisms oriented perpendicularly are used to interfere three reference waves and one object wave (Fig. 1(h-j)). The holographic fringes are modulated in amplitude (AM) and each amplitude contour corresponds to a given displacement of the lattice planes. It can provide live information if a sufficient fringe contrast is achieved. In any case, strain measurement requires a reference wave diffracted by a region of known lattice parameter (usually the substrate). One solution is the “tilted reference wave” (TRW) where a pre-specimen biprism and the condenser system are used to create an object-independent reference wave with an adjustable tilt angle [3]. Fig 2(a,b) is an example acquired in the vacuum and Fig. 2(c,d) shows the dark-field configuration for strain measurement. Finally, a pre-specimen biprism can also be useful for electron diffraction techniques. For instance, one can create two parallel half cones on a specimen (SCBED) with a controllable distance (Fig. 3(a)) [4]. Each spot in the diffraction pattern contains two lobes related to the regions crossed by the two probes. Fig. 1(b) shows an example of SCBED pattern series where the left and right lobes are related to unstrained and increasingly strained regions respectively.

[1] MJ Hÿtch et al, Nature 453 (2008), 1086–1089.
[2] T Denneulin et al, Ultramicroscopy 160 (2016), 98–109.
[3] F Röder et al, Ultramicroscopy 161 (2016), 23–40.
[4] F Houdellier et al, Ultramicroscopy 159, Part 1 (2015), 59–66.

Acknowledgments
This work was funded through the European Metrology Research Programme (EMRP) Project
IND54 Nanostrain. The EMRP is jointly funded by the EMRP participating countries within
EURAMET and the European Union. The authors acknowledge the European Union under the
Seventh Framework Programme under a contract for an Integrated Infrastructure Initiative
Reference 312483-ESTEEM2.
  • Lecture (Conference)
    16th European Microscopy Congress, EMC 2016, 28.08.-02.09.2016, Lyon, France

Permalink: https://www.hzdr.de/publications/Publ-24668
Publ.-Id: 24668


Electron holography by means of tilted reference waves

Röder, F.; Lubk, A.; Houdellier, F.; Denneulin, T.; Snoeck, E.; Hÿtch, M.
Off-Axis Electron Holography permits the direct reconstruction of amplitude and phase of electron waves elastically scattered by an object (see, e.g., [1]). The technique employs the Möllenstedt biprism to mutually incline an object modulated wave and a plane reference wave to form an interference pattern at the detector plane. Limited coherence of the electron beam in presence of aberrations attenuates high spatial frequencies of the object exit wave spectrum, which is illustrated by the sideband envelope function for a non-corrected TEM in Fig. 1a. In this work, we explore an extension of the conventional setup given by deliberately tilting the reference wave independent from the object wave. This allows the transfer of spatial frequencies beyond the conventional sideband information limit in Fig. 1a as predicted by a generalized transfer theory for Off-Axis Electron Holography [2]. This is because a reference wave tilted by q0 compensates the berration impact on the spatial frequency q0 of the object wave spectrum. The resulting transfer envelope for a tilt of q0x = -10/nm perpendicular to the post-specimen biprism is shown in Fig. 1b, where the contrast maximum of the total envelope (TCC) is located at q0x. Thus, an off-axis hologram series with varying reference wave tilt allows in principle a linear synthesis of an effective coherent aperture with a radius reaching out beyond the conventional information limit. Furthermore, an object-independent measurement of aberrations as well as dark-field electron holography can be realized using this setup. The experimental realization of an arbitrarily tilted reference wave is challenging and could be realized for the first time at the Hitachi HF3300C I2TEM at CEMES Toulouse for one direction [3]. We used an additional biprism placed in the illumination system. Three condenser lenses were adjusted to provide a demagnified image of the condenser biprism at the sample plane under parallel illumination (Fig. 2). The pre-specimen deflectors were adapted to maintain the incident wave vector of the object wave and to realize a tilt of the reference wave as a function of the condenser biprism voltage. Optimal condenser lens settings were found by means of paraxial ray tracing (Fig. 3) finally producing a mutual tilt of up to 20/nm at the object plane. We verified the kink-like phase modulation of the incident beam by means of holographic measurements. Contrast transfer theory including condenser aberrations and biprism instabilities was applied to explain detailed fringe contrast measurements. Finally, we have experimentally shown that dark-field holography [4] can be conducted with an object-independent reference.

[1] H Lichte et al, Rep. Prog. Phys. 71 (2008) 016102
[2] F Röder et al, Ultramic. 152 (2015) 63-74
[3] F Röder et al, Ultramic. 161 (2016) 23–40
[4] MJ Hÿtch et al, Nature 453 (2008), 1086–1089

Acknowledgments
We thank the Graduate Academy of the TU Dresden for the financial support. The research leading to these
results has received funding from the European Union Seventh Framework Programme under Grant Agreement
312483-ESTEEM2 (Integrated Infrastructure Initiative-I3).
  • Lecture (Conference)
    16th European Microscopy Congress, EMC 2016, 28.08.-02.09.2016, Lyon, Fracne

Permalink: https://www.hzdr.de/publications/Publ-24667
Publ.-Id: 24667


Direct holographic depth- and lateral- imaging of nanoscale magnets generated by ion impact

Röder, F.; Hlawacek, G.; Wintz, S.; Hübner, R.; Bischoff, L.; Lichte, H.; Potzger, K.; Lindner, J.; Fassbender, J.ORC; Bali, R.
The alloy Fe60Al40 is described by a paramagnetic B2 structure in its ordered phase, which transforms into a ferromagnetic A2 structure by chemical disordering that can be induced locally by ion irradiation [1,2]. This mechanism allows writing arbitrary magnetic nanostructures on paramagnetic thin films e.g. by means of a focused ion beam available in novel scanning ion microscopes. However, reproducible fabrication of nanoscale magnets requires knowledge about the depth and lateral distribution of the induced magnetization in dependence on irradiation parameters. Off-Axis Electron Holography provides suitable insights by revealing the local distribution of the projected magnetic flux density with nanometer resolution [3]. By means of the coherent superposition of an electron wave passing through the object with one passing through vacuum, interference fringes can be formed at the detector plane encoding the amplitude and phase of the electron wave. The phase of an electron wave shifted by electric and magnetic fields of the object permits direct field mapping at the nanometer scale. In cross-sectional samples of irradiated thin films, we studied the effect of the kinetic ion energy ranging from 5-30 keV on the depth distribution of the induced magnetization [4]. In agreement with irradiation damage simulations [2], we found a magnetized film adjacent to the ion entrance surface growing in depth with increasing kinetic ion energy. We conclude that a homogeneous magnetization depth distribution in a 40 nm thick film requires a kinetic Ne+ ion energy of at least 20 keV. The resolution of the ion beam nano-pattering is mainly limited by the effect of lateral ion scattering blurring the magnetization distribution at the pattern edges. To study this effect, we fabricated 500 nm wide magnetized stripes separated by non-ferromagnetic (i.e. non-irradiated) spacers (Fig. 1) using a focused Ne+ ion beam (2 nm probe size) at 25 keV in a helium ion microscope [5]. The flux distribution at the stripe facets is an indicator for the effect of lateral scattering but is difficult to directly interpret in terms of magnetization because of the superposition with stray fields. Therefore, we applied a magneto-static model for the field distribution around the nanoscale magnet as a function of the magnetization blurring, which returns a width of lateral scattering of about 20 nm fitting best to experimental results [4].

[1] J Fassbender et al, Phys. Rev. B 77 (2008) 174430.
[2] R Bali et al, Nanoletters 14 (2014) 435-441.
[3] H Lichte et al, Rep. Prog. Phys. 71 (2008) 016102.
[4] F Röder et al, Sci. Rep. 5 (2015) 16786.
[5] G Hlawacek et al, J. Vac. Sci. Technol. B 32 (2014) 020801.

Acknowledgments
We thank the Ion Beam Center at Helmholtz-Zentrum Dresden-Rossendorf for providing the necessary facilities.
The research leading to these results has received funding from the European Union Seventh Framework
Programme under Grant Agreement 312483 - ESTEEM2 (Integrated Infrastructure Initiative- I3).
  • Poster
    16th European Microscopy Congress, EMC 2016, 28.08.-02.09.2016, Lyon, France

Permalink: https://www.hzdr.de/publications/Publ-24666
Publ.-Id: 24666


Inducing confined magnetic regions in B2 materials using a nanofocussed light-ion beam

Bali, R.; Röder, F.; Hlawacek, G.; Wintz, S.; Heidarian, A.; Semisalova, A.; Hübner, R.; Bischoff, L.; Potzger, K.; Lichte, H.; Lindner, J.; Fassbender, J.ORC
The use of focussed beams of ions to induce strong saturation magnetization (Ms) can lead to unprecedented flexibility in rapidly producing modulated magnetic materials of desired geometry. True flexibility is achieved if the process is non-destructive i.e., Ms is activated at the point of ion impact. Furthermore, the ion is ideally chemically inert and of low mass, such that it escapes the lattice after undergoing the collision process with host atoms and coming to rest. Here we describe the possibility of using a nano-focussed beam of Ne+ ions to generate ferromagnetic phases within initially non-ferromagnetic B2 materials such as Fe60Al40 and Fe50Rh50. The transition occurs as the penetrating ions displace atoms, and the subsequent vacancy creation and recombination leading to the formation of the chemically disordered A2 structure, which is ferromagnetic. The beam has a diameter of ≈ 2 nm and the transformed region is confined to the interaction volume of the ions with the host atoms, with a diameter < 50 nm. Such an ion-beam is readily available in a He+-ion microscope (where Ne+ can also be loaded). The locally formed ferromagnetic nanostructures are embedded within the electrically conducting B2 precursor material. In the case of Fe60Al40 ferromagnetic regions of Ms = 780 kAm-1 [1] are embedded within a non-ferromagnetic matrix. For Fe50Rh50, ferromagnetic regions of Ms = 1000 kAm-1 [2] can be embedded within an antiferromagnetic matrix. The ion-induced B2 → A2 phase transition is the most viable route to achieving well-defined ferromagnetic nanostructures of desired geometry within non-ferromagnetic metallic matrices. We describe our recent direct nanoscale imaging of ion-induced magnetic regions [3] and our attempts to demonstrate possible applications in spin-transport and magnonic devices.
References:
[1] R. Bali, S. Wintz, F. Meutzner, R. Hübner, R Boucher, A. A. Ünal, S Valencia, A. Neudert, K. Potzger,
J. Bauch, F. Kronast, S. Facsko, J. Lindner, and J. Fassbender, Nano Letters 14, 2, 435 (2014).
[2] Alireza Heidarian, Rantej Bali, Jörg Grenzer, Richard A. Wilhelm, Rene Heller, Oguz Yildirim, Jürgen Lindner and
Kay Potzger, Nucl. Instrum. Methods Phys. Res. B 358, 251-254 (2015).
[3] Falk Röder, Gregor Hlawacek, Sebastian Wintz, René Hübner, Lothar Bischoff, Hannes Lichte, Kay Potzger,
Jürgen Lindner, Jürgen Fassbender, and Rantej Bali, under review, Scientific Reports (2015).
Keywords: Phase transitions, Chemical disorder, Ion beams.
  • Lecture (Conference)
    13th Joint MMM-Intermag Conference, 11.-15.01.2016, San Diego, USA

Permalink: https://www.hzdr.de/publications/Publ-24665
Publ.-Id: 24665


PRONTOX - proton therapy to reduce acute normal tissue toxicity in locally advanced non-small-cell lung carcinomas (NSCLC): study protocol for a randomised controlled trial

Zschaeck, S.; Simon, M.; Löck, S.; Troost, E. G. C.; Stützer, K.; Wohlfahrt, P.; Appold, S.; Makocki, S.; Bütof, R.; Richter, C.; Baumann, M.; Krause, M.
BACKGROUND:
Primary radiochemotherapy with photons is the standard treatment for locally advanced-stage non-small cell lung cancer (NSCLC) patients. Acute radiation-induced side effects such as oesophagitis and radiation pneumonitis limit patients' quality of life, and the latter can be potentially life-threatening. Due to its distinct physical characteristics, proton therapy enables better sparing of normal tissues, which is supposed to translate into a reduction of radiation-induced side effects.
METHODS/DESIGN:
This is a single-centre, prospective, randomised controlled, phase II clinical trial to compare photon to proton radiotherapy up to 66 Gy (RBE) with concomitant standard chemotherapy in patients with locally advanced-stage NSCLC. Patients will be allocated in a 1:1 ratio to photon or proton therapy, and treatment will be delivered slightly accelerated with six fractions of 2 Gy (RBE) per week.
DISCUSSION:
The overall aim of the study is to show a decrease of early and intermediate radiation-induced toxicity using proton therapy. For the primary endpoint of the study we postulate a decrease of radiation-induced side effects (oesophagitis and pneumonitis grade II or higher) from 39 to 12%. Secondary endpoints are locoregional and distant failure, overall survival and late side effects.
TRIAL REGISTRATION:
Registered at ClinicalTrials.gov with Identifier NCT02731001 on 1 April 2016.
Keywords: Locally advanced; Non-small-cell lung cancer (NSCLC); Phase II trial; Photon radiotherapy; Proton radiotherapy; Randomised clinical trial; Toxicity

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Publ.-Id: 24664


Self Assembly of Magnetic Nanoclusters in Diamond-Like Carbon: A Diffusion Enhanced Process Activated by Collision Cascades

Markwitz, A.; Williams, G.; Osipowicz, T.; Hübner, R.; Saumitra, V.; Gupta, P.
Improvements in device performance are limited by our capabilities in fabrication techniques. To overcome the current barriers, we need a method to atomically position and configure impurities in sub-micron scale devices. Our recent investigations show that this may be possible. By using hydrogen as atomic “lubricants” during ion implantation, we were able to engineer the position of dopants/impurities in near surface region of semiconducting materials in nanometre level precision. We are currently studying cobalt implantation into diamond-like carbon (DLC) system. The implantation profile of cobalt ions matched theoretical prediction when DLC was lacking of hydrogen. However, when hydrogen was introduced into the base material, the implantation profile was found to be strikingly different. On closer examination it was found that that the impurity atoms track the profile of hydrogen within the material. This brings us to an interesting hypothesis: the physical and chemical interaction between the impurities and the hydrogen atoms allows rearrangement of the impurities by increasing their mobility. The remarkable aspect of this result is that the dopants were manipulated using a room temperature process. This ability will have wide implications for many industries such as: engineering dopant profiles in semiconductor devices, positioning magnetic nanoparticles in magnetic sensors and data storage devices, increasing the capacity of hydrogen storage for fuel cell applications.
  • Invited lecture (Conferences)
    International Union of Materials Research Societies – International Conference on Electronic Materials, IUMRS-ICEM 2016, 04.-08.07.2016, Singapore, Singapore

Permalink: https://www.hzdr.de/publications/Publ-24663
Publ.-Id: 24663


Self-ordered Ge-based core/shell quantum dots in glass matrix

Buljan, M.; Nekic, N.; Sancho Paramon, J.; Jercinovic, M.; Bogdanovic-Radovic, I.; Grenzer, J.; Hübner, R.; Bernstorff, S.
Simple fabrication processes of Ge-based nanostructures in glasses are very interesting due to the highly tuneable electronic structure and many relevant applications. We address the recent advances in the production of regularly ordered Ge/Si and Ge/metal core/shell nanostructures formed by magnetron sputtering deposition in glass alumina matrix [1]. The regular ordering of these nanostructures is achieved by the self-ordering growth regime that occurs under specific deposition conditions [2]. We have developed the theory and software for the analysis of such materials by small grazing incidence angle x ray scattering (GISAXS) [3].
The light absorption properties of these films are significantly different compared to films that form quantum dot lattices of the pure Ge, Si, metal or a solid solution of the constituents. The Ge/Si core/shell quantum dots show a strong narrow absorption peak that characterizes a type II confinement in accordance with the theoretical predictions. In addition, we show that the peak position and width depend strongly on the size of Ge core and Si shell [4]. These materials are very interesting for the application in quantum dot solar cells.
[1] M. Buljan, et al., Nanotechnology 26 065602 (2015).
[2] M. Buljan, et al., J. Appl. Cryst. 46, 1490-1500 (2013).
[3] M. Buljan, et al., Acta Cryst. A, 68, 124 (2012); http://homer.zpr.fer.hr/gisaxstudio/doku.php
[4] N. Nekic, et al., (in preparation)
  • Invited lecture (Conferences)
    20th International Vacuum Congress (IVC-20), 21.-26.08.2016, Busan, Korea

Permalink: https://www.hzdr.de/publications/Publ-24662
Publ.-Id: 24662


Comment on „Dosimetric comparison of stopping power calibration with dual-energy CT and single-energy CT in proton therapy treatment planning“ [Med. Phys. 43(6), 2845-2854 (2016)]

Wohlfahrt, P.ORC; Möhler, C.ORC; Greilich, S.; Richter, C.
A dosimetric comparison of proton treatment planning based on single-energy CT (SECT) and dual-energy CT (DECT) was recently published by Zhu and Penfold in Medical Physics. In this study, the polymer phantom Catphan Module 404 (The Phantom Laboratory, Salem, NY, USA) of known material composition was used to demonstrate an improved accuracy of dose calculation using DECT instead of SECT. To confirm this result in a more realistic human case, the authors show for a single axial CT slice the dose difference of a SECT- and DECT-based treatment plan using the anthropomorphic phantom Rando (Radiological Support Devices, Inc., CA, USA) of unknown composition.
Keywords: dual-energy CT, proton therapy, range uncertainty, absolute range verification

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Permalink: https://www.hzdr.de/publications/Publ-24660
Publ.-Id: 24660


What is needed to demonstrate the benefit of dual-energy CT for particle treatment planning?

Möhler, C.ORC; Wohlfahrt, P.ORC; Richter, C.; Greilich, S.
Purpose/Objective:
To thoroughly understand and quantify the benefit of dual-energy CT (DECT) for the reduction of range uncertainty in particle treatment planning.

Material/methods:
In a multi-step procedure, DECT-based direct prediction of stopping-power ratios (SPRs) was improved in accuracy, robustness and clinical applicability by optimizing CT scan protocols, as well as post-reconstruction voxelwise SPR calculation algorithms. Subsequently, it was verified by three independent, yet complementary, studies in comparison to the current clinical standard (single-energy CT, SECT): (A) a relative comparison in patient cases; two absolute comparisons in (B) a controlled experimental setting measuring photon and ion absorption in animal tissues and tissue base components; and in (C) an inhomogeneous head phantom providing a well-established ground truth (Figure 1).

Results:
For a large collective of proton therapy patients (A), substantial intra- and inter-patient variability in CT-number-to-SPR-conversion as well as relative range differences of about 1.5-2.5% between SECT- and DECT-based treatment plans were observed. Both reveal the relevance of accurate CT-based SPR prediction and the potential for improvement. While naturally missing in patient studies, a reliable ground truth was provided in (B) and (C) to allow for absolute evaluations of SPR accuracy. The DECT method hereby proved capable to correctly predict SPR of homogenized animal tissues, tissue base components and the tissue substitutes in the anthropomorphic head phantom within measurement uncertainty.

Conclusion:
Only with the all-encompassing combination of theoretical considerations, lab experiments and the analysis of patient data, we are able to demonstrate clinically relevant reduction of range uncertainty with DECT-based treatment planning.

All authors contributed equally.
Keywords: dual-energy CT, proton therapy, particle therapy, range uncertainty
  • Lecture (Conference)
    56th Annual Conference of the Particle Therapy Co-operative Group (PTCOG), 08.-13.05.2017, Kanagawa, Japan

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Permalink: https://www.hzdr.de/publications/Publ-24659
Publ.-Id: 24659


A novel metal flow imaging using electrical capacitance tomography

Wondrak, T.; Soleimani, M.
The measurement of gas-liquid metal two phase flow is a challenging task due to the opaqueness and the high temperatures. For instance, during continuous casting of steel the distribution of argon gas and liquid steel in the submerged entry nozzle is of high interest, since it influences the quality of the produced steel. In this paper we present the results of a feasibility study for applying the electrical capacitance tomography (ECT) to detect the outer surface of a liquid metal stream. The results of this study are the basis for the development of a new contactless sensor which should be able to detect the outer shape of a liquid metal using ECT and the bubbles inside the jet at the same time using mutual inductance tomography.
Keywords: electrical capacitance tomography, liquid metal, surface detection

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Publ.-Id: 24658


Improved Efficiency by Adaptive Processing

van den Boogaart, K. G.; Gutzmer, J.; Reuter, M. A.; Tolosana Delgado, R.
- Get more value out of the ground
- Pick-and-choose your required tools based on NPV established criteria
- Understand how the realized value depends on you as a manager and investor
Keywords: NPV, Adaptive Processing, Optimisation
  • Lecture (others)
    Mines & Technology, 29.11.-01.12.2016, London, Great Britain

Permalink: https://www.hzdr.de/publications/Publ-24657
Publ.-Id: 24657


What CEOs and Investors should know about process optimization

van den Boogaart, K. G.; Gutzmer, J.; Reuter, M. A.; Tolosana Delgado, R.
Geometallurgy, long term mine planing, automated scheduling and other instances of software assisted process control and optimization rapidly gain importance in the mining sector. Decisions are taken based on big data and predictive models. Comparisons show substantial - but not always positive - effects on NPV, reliability, efficiency and recovery. Automated optimization is however not a technology like every other. It changes how we approach decision making and can easily gain or lose big money. CEOs and investors need to be aware of the chances, the pitfalls and the fundamental mechanisms of this industrial transformation. The presentation will demonstrate some of the relevant effects and principles on worked examples and extract the important implications for leading engineers, CEOs and investors. It shows how in this context disregarding uncertainty ruins your company, how classical KPIs and company structures cut the NPV, and why investors need to ask new questions. But it also shows how a rigorous and integrated approach to decisions making can help to increase net profit substantially. Leading the mining business into the 4th industrial revolution requires a deep understanding of these effects. Let's get started.
Keywords: Adaptive Processing, Geometallurgy, NPV
  • Lecture (others)
    PDAC, Prospectors and Developers Conference, 05.-08.03.2017, Toronto, Canada

Permalink: https://www.hzdr.de/publications/Publ-24656
Publ.-Id: 24656


Ionospheric tomography by gradient-enhanced kriging with STEC measurements and ionosonde characteristics

Minkwitz, D.; van den Boogaart, K. G.; Gerzen, T.; Hoque, M.; Hernandez-Pajares, M.
The estimation of the ionospheric electron density by kriging is based on the optimization of a parametric measurement covariance model. First, the extension of kriging with slant total electron content (STEC) measurements based on a spatial covariance to kriging with a spatial-temporal covariance model, assimilating STEC data of a sliding window, is presented. Secondly, a novel tomography approach by gradient enhanced kriging (GEK) is developed. Beyond the ingestion of 5 STEC measurements, GEK assimilates ionosonde characteristics providing peak electron density measurements as well as gradient information. Both approaches deploy the 3D electron density model NeQuick as a priori information and estimate the covariance parameter vector within a maximum likelihood estimation for the dedicated tomography time stamp. The methods are validated in the European region for two periods covering quiet and active ionospheric conditions. The kriging with spatial and spatial-temporal covariance model is analysed regarding its capability to reproduce STEC, differential STEC and foF2. 10 Therefore the estimates are compared to the NeQuick model results, the 2D TEC maps of the International GNSS Service and the DLR’s Ionospheric Monitoring and Prediction Center, and in case of foF2 to two independent ionosonde stations. Moreover, simulated STEC and ionosonde measurements are used to investigate the electron density profiles estimated by the GEK in comparison to a kriging with STEC only. The results indicate a crucial improvement of the initial guess by the developed methods and point out the potential compensation of a bias in the peak height hmF2 by means of GEK.
Keywords: STEC, VTEC, Geostatistics, Kriging of functionals

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Publ.-Id: 24655


Measurements pf the diameter of rising gas bubbles by means of the ultrasound transit time technique

Richter, T.; Wondrak, T.; Eckert, K.
This study presents ultrasound transit time technique (UTTT) measurements of single Ar bubbles rising in Galinstan under an applied magnetic field. Two setups were used to analyze the bubble rise, which led to different bubble trajectories. UTTT was able to visualize the bubble trajectory and to measure the bubble diameters. Due to the straightening of the bubble trajectories with increasing magnetic field, variation of the apparent bubble diameter were detected.
  • Poster
    10th PAMIR International Conference -- Fundamental and Applied MHD, 20.-24.06.2016, Cagliari, Italia
  • Contribution to proceedings
    10th PAMIR International Conference -- Fundamental and Applied MHD, 20.-24.06.2016, Cagliari, Italia, 978-88-90551-93-2, 542-546

Permalink: https://www.hzdr.de/publications/Publ-24654
Publ.-Id: 24654


Contactless inductive flow tomography for a simplified model of Czochralski crystal growth

Wondrak, T.; Pal, J.; Stefani, F.; Eckert, S.
In the Czochralski crystal growth the poloidal flow structure in the melt just below the meniscus plays a key role for the quality of the crystal. In order to investigate the applicability of the contactless inductive flow tomography to such a configuration, we equipped a modified Rayleigh-Benard setup with an axial excitation magnetic field and 20 magnetic field sensors. In this paper we present measurements of the flow induced magnetic field perturbations for several temperature gradients between the cooled top and the heated bottom. Typical features of the thermally driven turbulent flow could be detected in the magnetic field measured around the fluid vessel. Additionally, we will show first reconstructions of the flow.
  • Poster
    10th PAMIR International Conference -- Fundamental and Applied MHD, 20.-24.06.2016, Cagliari, Italia
  • Contribution to proceedings
    10th PAMIR International Conference -- Fundamental and Applied MHD, 20.-24.06.2016, Cagliari, Italia, 978-88-90551-93-2, 346-350

Permalink: https://www.hzdr.de/publications/Publ-24653
Publ.-Id: 24653


Dry calibration of a new generation local Lorentz force flowmeter

Hernandez, D.; Karcher, C.; Wondrak, T.
Local Lorentz force velocimetry (LFV) is a local velocity measurement technique for liquid metals. Due to the interaction between an electrically moving liquid and an applied magnetic field, eddy currents and flow-braking Lorentz forces are induced within the fluid. Due to Newtons’s third law, a force of the same magnitude acts on the source of the applied magnetic field which is in our case a permanent magnet. The magnet is connected to a new generation L2F2 that has been especially developed to record all these three force and three torque components. This sensor has already been tested at a continuous casting model with a 15 mm cubic magnet providing an insight of the 3-D velocity distribution of GaInSn near the wide face of the mold. For a better understanding of these results, especially regarding torque sensing, we propose dry experiments which consist on replacing the flowing liquid by a moving solid. In this kinematic approach, where the velocity field is already given, we are able to decrease considerably the variability and the noise of the measurements providing an accurate calibration of the system. In this paper we present the numerical results using a rotating disc made of aluminum and two different magnet systems that move across the plane of its axis of rotation.
  • Poster
    10th PAMIR International Conference -- Fundamental and Applied MHD, 20.-24.06.2016, Cagliari, Italia
  • Contribution to proceedings
    10th PAMIR International Conference -- Fundamental and Applied MHD, 20.-24.06.2016, Cagliari, Italia, 978-88-90551-93-2, 198-202

Permalink: https://www.hzdr.de/publications/Publ-24652
Publ.-Id: 24652


Visualization of the global flow structure in a modified Rayleigh-Bénard setup using the contactless inductive flow tomography

Wondrak, T.; Pal, J.; Stefani, F.; Galindo, V.; Eckert, S.
Rayleigh-Bénard (RB) convection is not only a classical problem in fluid dynamics, but also plays an important role in many metallurgical applications, like Czochralski crystal growth. The measurement of the flow field and of the dynamics of the emerging large-scale circulation (LSC) in liquid metals is a challenging task due to the opaqueness and the high temperature of the melt. The contactless inductive flow tomography (CIFT) is able to visualize the mean three dimensional flow structure in liquid metals by measuring the flow induced magnetic field perturbations under the influence of one, or several, applied magnetic fields. In this paper, the first measurements of the flow induced magnetic field in a RB setup, which can be used to investigate the dynamics of the LSC, will be presented. Additionally, the quality of the reconstruction of the three dimensional flow field, for such a configuration, will be investigated numerically.
Keywords: Contactless inductive flow tomography, flow measurement, liquid metal
  • Contribution to proceedings
    WCIPT8 - 8th World Congress on Industrial Process Tomography, 26.-29.09.2016, Foz do Iguacu, Brasilia
  • Lecture (Conference)
    WCIPT8 - 8th World Congress on Industrial Process Tomography, 26.-29.09.2016, Foz do Iguacu, Brasilia

Permalink: https://www.hzdr.de/publications/Publ-24651
Publ.-Id: 24651


Detection of the shape of liquid metals using electrical capacitance tomography

Wondrak, T.; Zhang, M.; Soleimani, M.
In metallurgical processes gas-liquid metal two-phase flows play an important role. The monitoring of single bubbles in a free liquid metal jet is quite challenging due to the high temperature and the opaqueness of the melt. In this paper we investigate the applicability of the electrical capacitance tomography (ECT) for imaging the outer surface of a liquid metal strand. The results of this feasibility study are the basis for the development of a new sensor combining ECT for the detection of the outer shape of the jet and mutual induction tomography (MIT) for the detection of bubbles inside the jet at the same time. In order to show the principal applicability, we will present a first static measurement of the level of the eutectic alloy GaInSn in a pipe. An ECT sensor with 12 electrodes was mounted on the outer surface of an acrylic glass pipe with inner diameter of 70 mm. For different levels of liquid metal in the cross section of the sensor, the capacitance was measured and the image was reconstructed. Additionally, we will shorty discuss the challenges of the application of ECT in this setup, such as the wettability of the material of the pipe with liquid metal.
Keywords: electrical capacitance tomography, liquid metal, surface detection
  • Contribution to proceedings
    WCIPT8 - 8th World Congress on Industrial Process Tomography, 26.-29.09.2016, Foz do Iguacu, Brasilia
  • Lecture (Conference)
    WCIPT8 - 8th World Congress on Industrial Process Tomography, 26.-29.09.2016, Foz do Iguacu, Brasilia

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Permalink: https://www.hzdr.de/publications/Publ-24650
Publ.-Id: 24650


Experimental setup for first in-phantom measurements of magnetic field effects on dose distributions of proton pencil beams

Hoffmann, A.; Schellhammer, S.; Gantz, S.; Zeil, K.; Lühr, A.
Purpose: To present an experimental measurement setup for MR-integrated proton therapy (MRiPT) dosimetry studies of magnetic field-induced dose distortion effects on slowing down proton pencil beams in a tissue-equivalent phantom.

Methods: A 0.95 T NeFeB permanent dipole magnet was utilized to generate a transverse magnetic field over a 4x20x15 cm3 air gap. A PMMA slab phantom with Gafchromic EBT3 film was placed inside the air gap to measure planar dose distributions of 80-180 MeV proton pencil beams. Integrated depth-dose curves, beam trajectories, range and deflection of the Bragg peak were extracted from the films. A 3D finite-element model -- developed to generate magnetic vector field data -- was experimentally validated by Hall probe magnetometry. Repeated measurements of the magnetic field strength were performed to assess its stability during irradiation experiments.

Results: The modelled magnetic vector field data differed less than 2% from the measured data. Magnetic field-induced beam deflection was clearly observed from the planar dose distributions (Fig. 1). Integrated depth-dose curves showed a similar form in comparison to measurements without magnetic field. Lateral displacement of the Bragg peak increased with energy from 1 to 10 mm for 80 and 180 MeV, respectively (Fig. 2). Spot measurements of the magnetic field strength showed high reproducibility (sigma=3 mT) and no effects of radiation-induced degradation.

Conclusion: For the first time, a measurement setup to study magnetic field-induced proton beam dose effects in a film phantom has been realized. The method is instrumental for building and validating Monte Carlo beam models for future MRiPT concepts.
Keywords: Proton therapy, magnetic field, film dosimetry
  • Open Access Logo Abstract in refereed journal
    International Journal of Particle Therapy 4(2017)1, 58-58

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Permalink: https://www.hzdr.de/publications/Publ-24649
Publ.-Id: 24649


Recent developments on contactless inductive flow tomography for continuous casting

Wondrak, T.; Ratajczak, M.; Stefani, F.; Timmel, K.; Eckert, S.
In continuous casting the flow of the liquid steel in the mold has great impact on the quality of the produced steel. During casting even a rough knowledge of the flow field would be highly desirable in order to control process parameters or electromagnetic actuators. The high temperature of the liquid steel recommends a contactless measurement technique.
The contactless inductive flow tomography (CIFT) is able to reconstruct the dominating two-dimensional flow structure in a slab casting mold by measuring the perturbation of an applied magnetic field outside the mold and solving a linear inverse problem. In this paper we will give an overview of the application of CIFT to two models of continuous casting available at the Helmholtz-Zentrum Dresden – Rossendorf. For a physical model of a mold with a cross section of 140 mm × 35 mm we present the new measurement system using induction coils and show preliminary measurements of the flow field in the mold in the presence of a magnetic brake. In addition, we show first reconstructions of the flow field in a mold with the cross section of 400 mm × 100 mm demonstrating the upward scalability of CIFT. We will conclude with recent developments towards an implementation in industry.
  • Lecture (Conference)
    SCANMET V - 5th International Conference on Process Development in Iron and Steelmaking, 12.-16.06.2016, Lulea, Schweden
  • Contribution to proceedings
    SCANMET V - 5th International Conference on Process Development in Iron and Steelmaking, 12.-16.06.2016, Lulea, Schweden
    Book of abstracts, 978-91-639-1232-7, 131

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Permalink: https://www.hzdr.de/publications/Publ-24648
Publ.-Id: 24648


Contactless inductive flow tomography: inverse problem and applications

Wondrak, T.; Ratajczak, M.; Stefani, F.
In many industrial applications dealing with liquid metals even a rough knowledge of the flow field of the melt would be of high value. For instance, in continuous casting of steel the flow of the melt in the upper region of the mold is very important for the quality of the produced steel, regarding surface defects or the number of inclusions. The high temperatures and the chemical aggressiveness of liquid melts recommend contactless measuring techniques. Well-established optical methods like particle image velocimetry are not applicable, because of the opaqueness of the melt.
Due to the high electrical conductivity of liquid metals, inductive methods can be used. One of them is the Contactless Inductive Flow Tomography (CIFT) which allows the reconstruction of the mean three-dimensional flow structure of conducting liquids. CIFT works by applying one or more magnetic fields to the melt and measuring the flow induced perturbation of those fields outside the fluid volume. From these measurements the mean three dimensional velocity field can be reconstructed by solving a linear inverse problem similar to magnetoencephalography. In order to handle the non-uniqueness, Tikhonov regularization in combination with the L-curve method is used.
In this paper we will give an overview about the mathematical foundation of CIFT and delineate the linear inverse problem. In order to illustrate the numerical model and the regularization, we will show numerical and physical results of a model of a continuous caster and of a Rayleigh-B ́enard convection setup. Complementary Ultrasound Doppler Velocimetry measurements will be shown to be in good agreement with the reconstructed flow using CIFT. We will conclude with a short overview of the challenges to measure the flow induced magnetic field perturbations, which are usually about 3 to 4 magnitudes smaller than the applied magnetic field.
  • Lecture (Conference)
    22nd Inverse Days 2016, 13.-15.12.2016, Kuopio, Finnland

Permalink: https://www.hzdr.de/publications/Publ-24647
Publ.-Id: 24647


First experimental results of applying the contactless inductive flow tomography to a thermally driven convection problem motivated by Czochralski crystal growth

Wondrak, T.; Pal, J.; Stefani, F.; Eckert, S.
In Czochralski crystal growth (CZ) the flow structure of the liquid silicon in the crucible and especially below the meniscus plays an important role for the quality of the grown crystal, because it controls the mass flow and the temperature gradient. A direct measurement of the flow would be highly desirable. However, the melt temperature of more than 1420°C, its corrosive impact on most materials, and the high demands on its purity, makes the flow measurement a complicated task. The contactless inductive flow tomography (CIFT) is able to reconstruct the approximate flow structure in conducting liquids [1]. Exposing the liquid to one or multiple applied magnetic fields and measuring the flow induced magnetic field around the fluid volume, it is possible to infer the velocity field by solving a linear inverse problem with appropriate regularization techniques. Great challenges for applying CIFT to the Cz process are, first, the small poloidal melt velocities in the order of a few cm/s and, second, the large distance between the liquid silicon and the magnetic field sensors which are located outside the puller. After having carried out successfully some preliminary magnetic field measurements at a real industrial Cz puller, we are presently evaluating the applicability of CIFT for small velocities.
A modified Rayleigh-Bénard (RB) setup has been chosen, which was already used to model and control temperature fluctuations in a Cz setup [2]. The growing crystal rod is simulated by a “cold finger” placed on the top of the cylindrical geometry. The diameter of the cold finger is about one third smaller than the heated bottom part. As working fluid GaInSn was used. Large efforts were made to adapt CIFT to the experimental setup in order to compensate thermal expansion during the measurement.
We will present preliminary results which demonstrate the applicability of CIFT on thermally driven convection systems. Typical features of the thermally driven turbulent flow were detected in the magnetic field measurements and were also verified by simultaneous temperature measurements recorded by small thermocouples placed in the vicinity of the rim of the cold finger.

References
1. F. Stefani, G. Gerbeth, T. Gundrum, Physical Review E, 70 (2004), 056306
2. A. Cramer, M. Röder, J. Pal, G. Gerbeth, Magnetohydrodynamics, 46 (2010), 353-361
  • Poster
    1st German Czechoslovak Conference on Crystal Growth - GCCCG-1, 16.-18.03.2016, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24646
Publ.-Id: 24646


3D Druck – ein anschauliches Präsentationsmittel für geophysikalische Inhalte

Menzel, P.; Götze, H.-J.; Schmidt, S.; Steinberg, A.
Für die öffentliche Kommunikation geophysikalischer Arbeiten spielt eine anschauliche Präsentation der Sachverhalte eine entscheidende Rolle. Seit in den 1980er Jahren erste Ansätze für Rapid Prototyping vorgestellt wurden, hat sich die Technologie von 3D Druckern stetig weiterentwickelt und wird inzwischen regelmäßig in verschiedenen wissenschaftlichen Disziplinen von den Ingenieurswissenschaften bis hin zu Medizin und Chemie eingesetzt, um Vorserien-Prototypen, Bau- und Ersatzteile sowie Anschauungsmodelle günstig und schnell produzieren zu können. In den Geowissenschaften und speziell in der Geophysik wurden diese Verfahren bisher sehr selten, zur Anfertigung von Ersatz- und Zusatzteilen für verschiedene Messinstrumente, verwendet. Im Rahmen des DGMK-Projektes TiPot3D wurde in der Arbeitsgruppe Geophysik und Geoinformation der Christian-Albrechts-Universität zu Kiel ein 3D Drucker Ultimaker² angeschafft und steht dort seit 2013 für spezielle geophysikalische Anwendungen bei der Interpretation und für die Visualisierung von 3D Modellen der Erdkruste zur Verfügung. Für die Präsentation von Daten nach einem 3D Druck ist kein zusätzliches Equipment notwendig. Diese neue Visualisierungsmöglichkeit bietet sich somit vor allem dann als Kommunikationsmedium an, wenn die Präsentation z.B. mittels 3D Computergrafik nicht angemessen ist oder technisch nicht in Frage kommt. Um Daten und Modelle mit Hilfe des 3D Drucks zu repräsentieren, müssen die Eingabedaten als digitale triangulierte Geometriemodelle vorliegen oder aber in diese überführt werden. Es wird anhand mehrerer unterschiedlicher Beispiele (z.B. 3D Untergrundmodelle aus Seismik und Gravimetrie, sowie Erdbebendeformationskarten) gezeigt, in welcher Weise geophysikalische Daten und Ergebnisse unterschiedlicher Komplexität für den 3D Druck aufbereitet und repräsentiert werden. Generell lassen sich die meisten geophysikalischen Datensätze mittels 3D Druck repräsentieren. Der zu betreibende Aufwand hängt dabei sowohl von der Komplexität der Eingabedaten, als auch vom kommunikativen Zweck und der beabsichtigten Größe des zu druckenden Datensatzes ab. Die gezeigten Ergebnisse haben sich vor allem für fachfremdes Publikum als ein eindrucksvolles Präsentationsmittel erwiesen.
Keywords: Geophysik, Visualisierung, 3D Druck
  • Poster
    77. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, 27.-30.03.2017, Potsdam, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-24645
Publ.-Id: 24645


Contactless inductive flow tomography for industrially relevant applications

Wondrak, T.; Ratajczak, M.; Stefani, F.; Pal, J.; Timmel, K.; Eckert, S.
The contactless inductive flow tomography (CIFT) allows reconstructing the mean 3-dimensional flow structure of liquid melts by measuring the flow induced perturbations of one or more applied magnetic fields. These measurements are utilized to infer the flow field by solving a linear inverse problem using an appropriate regularization. We will give an overview of the application of CIFT to two models of continuous casting available at the Helmholtz-Zentrum Dresden-Rossendorf and report recent developments towards an implementation in industry. Additionally, we present preliminary results of CIFT applied to a thermally driven flow with some similarity to Czochralski silicon crystal growth. Due to the low velocities in the order of 1 cm/s, the dynamic range of the measurement system has to be enhanced by about one order of magnitude in comparison with the continuous casting application.
  • Lecture (Conference)
    2016 TMS Annual Meeting & Exhibition, 14.-18.02.2016, Nashville (Tennessee), USA

Permalink: https://www.hzdr.de/publications/Publ-24644
Publ.-Id: 24644


First experimental insights into the transition from AMRI to HMRI

Seilmayer, M.ORC
In the last years the magnetorotational instability (MRI) was focused intensively by theory and experiments. It turns out that investigating the standard MRI (SMRI), with its magnetic field pointing perpendicular to the rotation direction, is very hard. It is only possible to get this type of instability in rather large (1 m-scale) or fast rotating (f > 10 Hz) cylinders. Beside that two other types of MRI were discovered[1, 2]. The helical and azimuthal MRI, which where successfully investigated in the laboratory with the PROMISE2 facility. This setup consists of two concentric cylinders, a current carrying rod on the axis producing Bϕ and a cylindrical coil providing Bz to the fluid. In the past, experiments proved the theory of each individual instability [3, 4].
With the improved magnetic field system the PROMISE3 setup gains advantage of a more homogeneous magnetic field. So it becomes possible now to observe the transition between these two instabilities. First we like to give a prove of function and show how the velocity distribution and other properties changed with the improved magnetic field. Next to that we like to present very first results on the mode transition form the AMRI unstable m = 1 regime to the HMRI unstable m = 0 case. Here we start in a AMRI unstable parameter set (Re = 1500, Ha = 100 and µ = Ωout /Ωin = 0.26). By increasing the axial magnetic field Bz the AMRI m = 1 mode is disturbed successively until it is completely damped. At a certain field strength the other m = 0 mode emerges which also disappears at higher fields.
Finally we can conclude that AMRI and HMRI still work in the modified experiment according to the theory. There is a possible transition region between these two instabilities. One open question is why the flow structure changes so significant for AMRI in comparison to the PROMISE2 campaign [3]. And would it be better to improve the field further?

References
[1] G. Rüdiger et al., AN, 328(10):1158-1161, 2007.
[2] G. Rüdiger et al., AN, 329(7):659-666, 2008.
[3] M. Seilmayer et al., PRL, 113(2):024505, 2014.
[4] F. Stefani et al., NJP, 9(8):295, 2007.
Keywords: AMRI, magnetic field, magnetohydrodynamic, experiment
  • Lecture (Conference)
    17th MHD Days, 30.11.-02.12.2016, Göttingen, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-24643
Publ.-Id: 24643


Modeling Traveling-wave Thomson scattering using PIConGPU

Debus, A.; Steiniger, K.; Pausch, R.; Huebl, A.; Schramm, U.; Cowan, T.; Bussmann, M.
Traveling-wave Thomson scattering (TWTS) laser pulses are pulse-front tilted and dispersion corrected beams that enable all-optical free-electron lasers (OFELs) up to the hard X-ray range. Electrons in such a side-scattering geometry experience the TWTS laser field as a continuous plane wave over centimeter to meter interaction lengths.
After briefly discussing which OFEL scenarios are currently numerically accessible, we detail implementation and tests of TWTS beams within PIConGPU (3D-PIC code) and show how numerical dispersion and boundary effects are kept under control.
Keywords: TWTS, FEL, free-electron laser, particle-in-cell code, PIC
  • Lecture (Conference)
    DPG Frühjahrstagung Darmstadt 2016, 14.-18.3.2016, Darmstadt, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24642
Publ.-Id: 24642


Scaling EUV and X-ray Thomson Sources to Optical Free-Electron Laser Operation with Traveling-Wave Thomson Scattering

Debus, A.; Steiniger, K.; Albach, D.; Loeser, M.; Pausch, R.; Roeser, F.; Schramm, U.; Siebold, M.; Bussmann, M.
Abstract
Traveling-Wave Thomson-Scattering (TWTS) provides optical undulators with hundreds to thousands of undulator periods from high-power, pulse-front tilted lasers pulses. These allow to realize optical free-electron lasers (OFELs) with state-of-the-art technology in electron accelerators and laser systems in TWTS. The talk focuses on experimental realization and the combination of TWTS and laser-wakefield acceleration allowing for ultra-compact, inherently synchronized and highly brilliant light sources.

Summary
Traveling-Wave Thomson-Scattering (TWTS) employs a side-scattering geometry where laser and electron propagation direction of motion enclose the interaction angle ϕ. Tilting the laser pulse front with respect to the wave front by half the interaction angle optimizes electron and laser pulse overlap by compensating the spatial offset between electrons and the laser pulse-front at the beginning of the interaction when the electrons are far from the laser pulse axis. The laser pulse-front tilt ensures continuous overlap over the whole laser pulse width while the electrons cross the laser beam path. TWTS thus allows to control the interaction length by the laser pulse width rather than laser pulse duration. Utilizing wide, petawatt class laser pulses allows to realize thousands of optical undulator periods.

The photon yield of TWTS sources can therefore be orders of magnitude higher than that of classic head-on Thomson sources. TWTS thereby remains compact and provides narrowband and ultra-short ultraviolet to γ-ray radiation pulses just as classic Thomson sources.

Two key features of TWTS allow for the realization of optical free-electron lasers (OFELs). First, it provides optical undulators with lengths required for microbunching and thus coherent radiation amplification. Second, the variability in interaction angle allows to control the electron beam quality requirements for a target radiation wavelength. This is used to reduce the electron beam quality requirements to a level technically feasible today. Small interaction angle scenarios (ϕ∼10∘) typically yield the best trade-off between requirements on electron beam quality, laser power and laser intensity stability.

In the talk we will show that TWTS OFELs emitting extreme ultraviolet radiation are realizable today with existing technology for electron accelerators and laser systems. Especially the ultra-low emittance of laser wakefield accelerated electron beams can be exploited to compensate for their one percent level energy spreads. We discuss an experimental setup to generate the tilted TWTS laser pulses. The method presented provides dispersion compensation, required due to angular dispersion, and is especially relevant when building compact, high-yield hard X-ray TWTS sources in large interaction angle setups.
Keywords: TWTS, FEL, free-electron laser, EUV, xray
  • Lecture (Conference)
    17th Advanced Accelerator Concepts Workshop, 31.07.-5.8.2016, National Harbor, MD, USA

Permalink: https://www.hzdr.de/publications/Publ-24641
Publ.-Id: 24641


Recent advances in PIConGPU methods for modeling lasers, ionization and radiation

Debus, A.; Pausch, R.; Garten, M.; Burau, H.; Huebl, A.; Widera, R.; Irman, A.; Schramm, U.; Bussmann, M.
Abstract
We present recent simulations of laser wakefield acceleration (LWFA) and nonlinear Thomson scattering performed with the fully relativistic 3D3V particle-in-cell code PIConGPU. These cover both experimental setups currently carried out at HZDR and setups beyond state-of-the-art experiments. We discuss the recent advances in our code that allowed performing these simulations and examine their physical implications in detail.

Summary
The simulations presented require a variety of algorithmic extensions to the standard particle-in-cell cycle. These include a laser implementation which allows more freedom in modifying the simulated laser to describe the experimentally available laser to a high degree of accuracy, including setups ranging from simple chirping to TWTS-type laser pulses. These extensions also encompass a variety of ionization schemes, including BSI and ADK, for which we will discuss the physical foundation and the performance implications. Our code also provides algorithms for both classical radiation reaction effects, based on Landau and Lifshitz, and QED recoil to include radiation losses, as they occur for example during betatron oscillation. Furthermore, PIConGPU also provides in-situ synthetic radiation diagnostics: a classical radiation diagnostic, based on Liénard-Wiechert potentials, that allows predicting coherent and incoherent radiation spectra simultaneously for hundreds of observation directions and thousands of frequencies and a just recently implemented extension to include QED based photon generation and electron recoil beyond the classical scope. Encompassing these new algorithms and still being able to reach performances that allow large scale parameter scans is crucial and was only possible by strictly following an in-situ approach and efficiently using the GPU hardware, which will be discussed in detail.

The simulation presented will cover the emission expected during nonlinear Thomson scattering as experimentally performed with the DRACO laser and the ELBE accelerator at HZDR. We will further discuss the simulated plasma dynamic, electron acceleration and resulting X-ray signatures from laser wakefield acceleration for various He/N gas mixture and compare these to experiments. Furthermore we will present a radiation sky map of LWFA containing various spectral signatures to diagnose the plasma dynamic and new accelerator schemes.
Keywords: PIC, PIConGPU
  • Poster
    17th Advanced Accelerator Concepts Workshop, 31.07.-5.8.2016, National Harbor, MD, USA

Permalink: https://www.hzdr.de/publications/Publ-24640
Publ.-Id: 24640


Monte Carlo simulations of magnetic field effects on proton dose distributions in a 1T measurement setup

Schellhammer, S. M.ORC; Oborn, B.; Lühr, A.; Gantz, S.; Bussmann, M.; Hoffmann, A. L.
For an integration of proton therapy and magnetic resonance Imaging (MRI), mutual effects of these two modalities need to be assessed. We studied the magnetic field-induced proton beam deflection as well as the radiation-induced activation and demagnetization of the magnet material by simulating irradiation experiments with a realistic magnet.

Geant4 Monte Carlo simulations were performed for 80-180 MeV proton pencil beams traversing the 0.95 T transverse magnetic field of a dipole magnet. A PMMA slab phantom containing a radiochromic EBT3 film was placed between the magnetic poles, such that the incident beams were stopped in the film plane (Fig. 1). The magnetic field was modelled using 3D finite-elements and validated by magnetometry. Beam trajectories were analyzed from the film’s planar dose distributions. Upper bounds for radioactivation were deduced by analyzing the most common mother nuclides, and demagnetization was assessed by relating the simulated magnet dose to previously published data.

Considerable magnetic field-induced dose distortions can be observed from the planar dose distributions, as depicted for a 140 MeV beam in Fig 2. Lateral displacement of the Bragg peak ranged from 1-11 mm for 80-180 MeV beams. Initial activation of the magnet material was less than 25 kBq, and the mean dose to the magnet poles was ~20 μGy when delivering a dose of 2Gy at the Bragg peak to the film.
These results indicate that the Lorentz force-induced dose distortions are substantial, and measurable with the presented setup. Radiation-induced activation and demagnetization effects are small but should be monitored during the irradiation experiments.
  • Poster
    PTCOG56 - 56th Annual Conference of the Particle Therapy Co-Operative Group, 11.-13.05.2017, Yokohama, Japan

Permalink: https://www.hzdr.de/publications/Publ-24639
Publ.-Id: 24639


Animal PET/MR - a modern tool for radiotracer development and molecular imaging

Brust, P.
Es ist kein Abstract vorhanden.
  • Invited lecture (Conferences)
    Kolloquien Thammasat University, Mahidol University, Chiang Mai University, 22.-31.10.2016, Bangkok, Thailand

Permalink: https://www.hzdr.de/publications/Publ-24638
Publ.-Id: 24638


Use of animal PET/MR for radiotracer development and molecular imaging

Brust, P.
Es ist kein Abstract vorhanden.
  • Invited lecture (Conferences)
    TransportDementia2, 02.-06.09.2016, Oslo, Norway

Permalink: https://www.hzdr.de/publications/Publ-24637
Publ.-Id: 24637


Effiziente Nutzung mineralischer und metallhaltiger Rohstoffe

Reuter, M. A.
Ziel dieses Workshops ist es, programmübergreifende Schnittstellen in der Materialforschung zu stärken und Synergien zu nutzen.
  • Invited lecture (Conferences)
    Materialien und Modelierung - Workshop, 08.-09.11.2016, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24636
Publ.-Id: 24636


Challenges in the analysis of mineral surfaces in flotation technology

Firkala, T.; Lederer, F.; Pollmann, K.; Rudolph, M.
Flotation is one of the most traditional and widely used technologies in industrial mineral processing. This methodology is based on changing the hydrophobic behaviour of the mineral surfaces using organic flotation collector molecules. The mineral – collector interactions in the flotation interface are very important for the detailed understanding of the technology, but presently they are practically unexplored. We present our concepts to study the flotation interface applying some ultrasensitive nanospectroscopic facilities of Helmholtz Institute Freiberg for Resource Technology and Helmholtz-Zentrum Dresden-Rossendorf.
  • Lecture (others)
    University of Applied Sciences Wildau, Department Seminar, 12.12.2016, Wildau, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24635
Publ.-Id: 24635


Experimental study on rise velocities of single bubbles in liquid metal under the influence of strong horizontal magnetic fields in a flat vessel

Strumpf, E.
The ascent of single argon bubbles with equivalent diameters (deq) between 3.43 and 6.28 mm is investigated at room temperature in a flat, cubic vessel by means of Ultrasound Doppler Velocimetry (UDV). GaInSn is used as a working liquid and magnetic flux intensities up to B ≈ 0.918 T are applied. A decelerating effect on the rise velocity is observed at lower, an accelerating effect at medium and a reduction at higher field strengths. Maximum velocities are achieved when N/CD ≈ 1, bubble paths are substantially rectilinear at N/CD > 2. The mean ascent velocities are compared with literature and data of this work as well of other publications is provided in tables.
Keywords: bubble, rise velocity, liquid metal, magnetic field, ultrasound

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Permalink: https://www.hzdr.de/publications/Publ-24634
Publ.-Id: 24634


Alpaka - One Programming Model for Parallel Kernel Acceleration of Heterogeneous Systems

Matthes, A.; Zenker, E.; Worpitz, B.; Widera, R.; Huebl, A.; Juckeland, G.; Knüpfer, A.; Nagel, W.; Bussmann, M.
Alpaka provides a uniform, abstract C++ interface to a range of parallel programming models. It can express multiple levels of parallelism and allows for generic programming of kernels either for a single accelerator device or a single address space with multiple CPU cores. The Alpaka abstraction of parallelization is influenced by and based on the groundbreaking CUDA abstraction of a multidimensional grid of blocks of threads. The four main execution hierarchies introduced by Alpaka are called grid, block, thread, and element level. The element level denotes an amount of work a thread needs to process sequentially. These levels describe an index space which is called work division.

Alpaka does not dictate any memory containers nor memory iterators, instead it is based on a simple pointer based memory model, allowing to allocate memory buffers device-wise and copy them between devices. This model provides full power over data structures and their data access and is totally data structure agnostic.

Separating parallelization abstraction from specific hardware capabilities allows for an explicit mapping of these levels to hardware. The current implementation includes mappings to programming models, called back-ends, such as OpenMP, CUDA, C++ threads, and boost fibers. Nevertheless, mapping implementations are not limited to these choices and can be extended or adapted for application-specific optimizations. Which back-end and work division to utilize is parameterized per kernel within the user code.

We have demonstrated platform and performance portability for the DGEMM benchmark, which provides consistently 20% of the theoretical peak performance on AMD, Intel, IBM, and NVIDIA hardware, being on par with the respective native implementations. Moreover, performance measurements of a real world application (PIConGPU, HASEonGPU, ISAAC) translated to Alpaka unanimously demonstrated that Alpaka can be used to write performance portable code.
Keywords: Heterogeneous computing, HPC, C++, CUDA, OpenMP, platform portability, performance portability
  • Lecture (others)
    GPU Technology Conference Europe, 28.-29.09.2016, Amsterdam, Niederlande

Permalink: https://www.hzdr.de/publications/Publ-24633
Publ.-Id: 24633


Quasiparticle Excitations in the Superconducting State of FeSe Probed by Thermal Hall Conductivity in the Vicinity of the BCS–BEC Crossover

Watashige, T.; Arsenijevic, S.; Yamashita, T.; Terazawa, D.; Onishi, T.; Opherden, L.; Kasahara, S.; Tokiwa, Y.; Kasahara, Y.; Shibauchi, T.; von Löhneysen, H.; Wosnitza, J.; Matsuda, Y.
There is growing evidence that the superconducting semimetal FeSe (Tc ∼ 8 K) is in the crossover regime between weak-coupling Bardeen–Cooper–Schrieffer (BCS) and strong-coupling Bose–Einstein-condensate (BEC) limits. We report on longitudinal and transverse thermal conductivities, κxx and κxy, respectively, in magnetic fields up to 20 T. The field dependences of κxx and κxy imply that a highly anisotropic small superconducting gap forms at the electron Fermi-surface pocket whereas a more isotropic and larger gap forms at the hole pocket. Below ∼1.0 K, both κxx and κxy exhibit distinct anomalies (kinks) at the upper critical field Hc2 and at a field H* slightly below Hc2. The analysis of the thermal Hall angle (κxyxx) indicates a change of the quasiparticle scattering rate at H*. These results provide strong support to the previous suggestion that above H* a distinct field-induced superconducting phase emerges with an unprecedented large spin imbalance.

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Permalink: https://www.hzdr.de/publications/Publ-24631
Publ.-Id: 24631


Ultrafast electronic response of graphene to a strong and localized electric field

Gruber, E.; Wilhelm, R. A.ORC; Petuya, R.; Smejkal, V.; Kozubek, R.; Hierzenberger, A.; Bayer, B. C.; Aldazabal, I.; Kazansky, A. K.; Libisch, F.; Krasheninnikov, A. V.; Schleberger, M.; Facsko, S.; Borisov, A. G.; Arnau, A.; Aumayr, F.
The way conduction electrons respond to ultrafast external perturbations in low dimensional materials is at the core of the design of future devices for (opto)electronics, photodetection and spintronics. Highly charged ions provide a tool for probing the electronic response of solids to extremely strong electric fields localized down to nanometre-sized areas. With ion transmission times in the order of femtoseconds, we can directly probe the local electronic dynamics of an ultrathin foil on this timescale. Here we report on the ability of freestanding single layer graphene to provide tens of electrons for charge neutralization of a slow highly charged ion within a few femtoseconds. With values higher than 1012 A cm 2, the resulting local current density in graphene exceeds previously measured breakdown currents by three orders of magnitude. Surprisingly, the passing ion does not tear nanometre-sized holes into the single layer graphene. We use time-dependent density functional theory to gain insight into the multielectron dynamics.
  • Open Access Logo Nature Communications 7(2016), 13948
    DOI: 10.1038/ncomms13948
  • Lecture (Conference)
    Ionenstrahltreffen, 13.-15.02.2017, Göttingen, Deutschland
  • Lecture (Conference)
    Frühjahrestagung der Deutschen Physikalischen Gesellschaft, Sektion Kondensierte Materie, 20.-24.03.2017, Dresden, Deutschland
  • Invited lecture (Conferences)
    Optical NanoSpectroscopy IV, 28.-31.03.2017, Lissabon, Portugal

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Permalink: https://www.hzdr.de/publications/Publ-24630
Publ.-Id: 24630


Electronic structure of UN based on specific heat and field-induced transitions up to 65 T

Troc, R.; Samsel-Czekala, M.; Pikul, A.; Andreev, A. V.; Gorbunov, D. I.; Skourski, Y.; Sznajd, J.
The 5f electrons of uranium in the uranium mononitride (UN) compound are described in the literature as either localized or fully itinerant. Motivated by these contradictory statements, we studied low-temperature specific heat and high-field magnetization of single-crystalline UN in magnetic fields up to 9 and 65 T, respectively. Our detailed analysis of the magnetic contribution to the specific heat of UN revealed that its real ground state is complex and the 5f electrons seem to have a dual nature; i.e., they possess simultaneously local and itinerant characters in two substates. High-field experiments allowed us to construct a tentative magnetic phase diagram of UN with a metamagnetic transition from antiferromagnetism to ferrimagnetism at a magnetic field as high as 58 T at 2 K. Such a field only enables a reversal of 1 of the 12 antiferromagnetically coupled ferromagnetic layers in the direction of the magnetic field. Any further steplike transitions require application of ever higher magnetic fields, which is beyond the experimental possibilities. We show that the magnetic phase diagram can be successfully reproduced considering a layer model of the Ising spins. That model allows rough estimation of a phase transition into fully induced ferromagnetism at a field as high as about 258 T. It gives rise to a giant coupling between ferromagnetically ordered layers in UN. The obtained characteristics are presented, together with the results of recent x-ray photoemission spectroscopy and transport property measurements. They are analyzed and compared with a number of earlier experiments and band structure calculations that were performed for this compound and are widely described in the literature. We show that different experiments probe different substates of the uranium 5f electrons in UN (itinerant or localized), which supports our hypothesis on their dual nature.

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Permalink: https://www.hzdr.de/publications/Publ-24629
Publ.-Id: 24629


Ultrasonic flow measurements in a 1:6 downscaled water mockup of the DRESDYN dynamo experiment

Gundrum, T.; Vogt, T.; Giesecke, A.; Herault, J.; Stefani, F.
The project DRESDYN (DREsden Sodium facility for DYNamo and thermohydraulic studies) conducted at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) provides a platform for a variety of liquid sodium experiments. Most ambitious experiment will be a precession driven dynamo experiment which consists of a large cylindrical cavity filled with liquid sodium that will simultaneously rotate around two axis. The experiment is motivated by the idea of a precession-driven flow as a complementary energy source for the geodynamo or the ancient lunar dynamo. The detailed knowledge of the flow structure in the precessing cylindrical vessel is of key importance for the prediction of the dynamo action. My presentation addresses experimental examinations with ultrasonic Doppler velocimetry in the low Reynolds region to validate numerical simulations.
Keywords: DRESDYN, sodium experiments, precession driven dynamo, ultrasonic Doppler velocimetry
  • Lecture (Conference)
    17th MHD Days, 30.11.-02.12.2016, Göttingen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24628
Publ.-Id: 24628


Comparison of single-field and robust multi-field IMPT plans for oropharynx carcinoma by an enhanced method of robustness analysis

Stützer, K.; Lin, A.; Kirk, M.; Lin, L.
Purpose:
Presentation of an enhanced robustness analysis and its application on single-field (SFO) and robust multi-field optimized (rMFO) plans for intensity modulated proton therapy (IMPT).

Material/Methods:
rMFO IMPT plans were optimized (Eclipse v13.7, Varian, Palo Alto, CA) for 11 oropharynx carcinoma patients, which had been treated post-surgery with SFO IMPT with simultaneous integrated boost prescription. Expected mean dose per voxel is calculated for minimal, 0% and maximal range uncertainty (RU), considering 19 setup error (SE) scenarios and their likelihood of occurrence. Voxel-wise boundary dose distributions are created from all 57 scenarios including systematic RU and random SE while also taking into account the averaging effect of fractionation to approximate realistic worst cases for the total treatment course. Dose error distributions for under- and overdosage with according ROI-specific metrics are derived from these boundary doses.

Results:
Nominal rMFO plans show improved CTV coverage and homogeneity while simultaneously reducing the average mean dose to the constrictor muscles, larynx and ipsilateral middle ear by 5.6Gy(RBE), 2.0Gy(RBE) and 3.9Gy(RBE), respectively. The comparison of SFO and rMFO boundary doses reveals slightly larger differences for these organs, and significantly lower brainstem maximum and ipsilateral parotid mean dose in rMFO plans. Many dose error metrics are significantly superior for rMFO plans.

Conclusions:
The nominal benefit of better CTV coverage and OAR dose sparing by rMFO compared to SFO plans is preserved under considerations of SE and RU. DVH bands and dose metrics from the boundary dose distributions will help to judge plan robustness in clinical routine.
  • Lecture (Conference)
    56th Annual Conference of the Particle Therapy Co-Operative Group, 08.-13.05.2017, Chiba, Yokohama, Nihon

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Permalink: https://www.hzdr.de/publications/Publ-24627
Publ.-Id: 24627


Recycling 4.0 A metallurgical perspective

Reuter, M. A.
Der Umgang mit Rohstoffen und Energie spielt für die industrielle Entwicklung Europas eine entscheidende Rolle. Darüber hinaus beeinflussen Entwicklungstrends wie Industrie 4.0, Energiewende, E-Mobility, Wasserstofftechnologie usw. die Nichteisenmetallurgie im Bereich der Prozesstechnik und Produkte. Dies wird in den nächsten Jahren neben einer rascheren Veränderung auf Verfahrensebene ebenfalls zu einer verstärkten Vernetzung von Disziplinen, wie der Rohstofftechnik, der Metallurgie sowie den Werkstoffwissenschaften führen, sodass auf dem Gebiet des Recyclings von komplexen Reststoffen und Produkten zukünftig ein entscheidender Schritt hinsichtlich höherer Ressourcen- und Energieeffizienz gelingen könnte. Daneben ist es besonders wichtig, dass Lehre und Forschung als Einheit weiterhin bestehen bleiben, um den Anforderungen in den erwähnten Bereichen hinsichtlich einer hochqualitativen Ausbildung gerecht zu werden.
  • Invited lecture (Conferences)
    Treffen der Nichteisenmetallurgie, 26.11.2015, Leoben, Österreich

Permalink: https://www.hzdr.de/publications/Publ-24626
Publ.-Id: 24626


Platinum-group mineral distribution of LG6 and LG6a chromitites of the western Bushveld Complex, South Africa

Bachmann, K.; Osbahr, I.; Gutzmer, J.
The Bushveld Complex (BVC) in South Africa hosts the majority of global resources of chromium and platinum group elements (PGE). A correlation between chromitite seams and PGE is exceptionally well expressed as all chromitite layers carry elevated levels of PGE. Furthermore, the Bushveld chromitite seams show a progressive and massive increase in PPGE (Pt, Pd, Rh) contents up sequence, whereas the IPGE (Os, Ir, Ru) values remain broadly constant or rise only slightly. This trend coincides with decreasing Cr/Fe of the chromitites resulting in a focus of mining the upper seams, namely the upper group (UG)-2 for PGE and the middle groups (MG)/ lower groups (LG) for chromite. In recent years, companies already commenced extracting PGE from the MGs and LGs as a by-product during and/or after chromite production. However, only few mineralogical studies about the siting of the PGE (in silicates, sulfides or discrete platinum-group minerals (PGM)) in the LGs and MGs are available. Furthermore, information about parameters such as variation of the proportions of PGM within the chromitite seams, PGM association and grain sizes are scarce. From a geometallurgical perspective, these fundamental parameters about modal mineralogy and microfabric of the PGM in the chromite ores are crucial.
The purpose of this study is to fill this knowledge gap for the western limb of the BVC by investigating drill cores of the LG6 and LG6a seams from the Thaba mine near Thabazimbi. The study follows systematic studies of Voordouw et al.. More than 30 polished thin sections from three drill cores were analyzed by mineral liberation analysis to determine both, the modal mineralogy and the contained PGM (>100 grains per section in average) as well as base metal sulfides in-situ. This work was complemented by detailed analysis of the silicates by electron probe microanalyzer. The PPGE-bearing minerals include various Pt-Pd-Rh sulfides and -alloys as well as a significant amount of PPGE arsenides, bismuthides, and antimonides. IPGE are bound in laurite as well as sulfarsenides with various composition. The PGM are associated with sulfides as well as chromite and minor silicates. Grain-sizes are typically small (below 10 µm, usually c. 5 µm and smaller).
Keywords: -
  • Lecture (Conference)
    1st GOOD meeting, 15.-18.03.2016, Freiberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24625
Publ.-Id: 24625


Platinum-group mineral composition and mineralogy of LG6 and LG6a chromitites of the western Bushveld Complex, South Africa

Bachmann, K.; Osbahr, I.; Krause, J.; Gutzmer, J.
The Bushveld Complex (BVC) in South Africa hosts the majority of global resources of chromium and platinum group elements (PGE). A correlation between chromitite seams and PGE is exceptionally well expressed as all chromitite layers carry elevated levels of PGE. Furthermore, the Bushveld chromitite seams show a progressive and massive increase in PPGE (Pt, Pd, Rh) contents up sequence, whereas the IPGE (Os, Ir, Ru) values remain broadly constant or rise only slightly. This trend coincides with decreasing Cr/Fe of the chromitites resulting in a focus of mining the upper seams, namely the upper group (UG)-2 for PGE and the middle groups (MG)/ lower groups (LG) for chromite. In recent years, companies already commenced extracting PGE from the MGs and LGs as a by-product during and/or after chromite production. However, only few mineralogical studies about the siting of the PGE (in silicates, sulfides or discrete platinum-group minerals (PGM)) in the LGs and MGs are available. Furthermore, information about parameters such as variation of the proportions of PGM within the chromitite seams, PGM association and grain sizes are scarce. From a geometallurgical perspective, these fundamental parameters about modal mineralogy and microfabric of the PGM in the chromite ores are crucial.


The purpose of this study is to fill this knowledge gap for the western limb of the BVC by investigating drill cores of the LG6 and LG6a seam from the Thaba mine near Thabazimbi. Currently, the deposit is mined for chromite by CRONIMET Chrome SA (Pty.) Ltd. The study follows systematic studies of Voordouw et al. More than 60 polished thin sections from three drill cores were analyzed by mineral liberation analysis to determine both, the modal mineralogy and the contained PGM (>100 grains per section in average) as well as base metal sulfides in-situ. This work was complemented by detailed analysis of the PGM, base metal sulfides (pentlandite, pyrite, pyrrhotite) and silicates by electron probe microanalyzer. The PPGE-bearing minerals include various Pt-Pd-Rh sulfides and -alloys as well as a significant amount of PPGE arsenides, bismuthides, and antimonides. IPGE are bound in laurite as well as sulfarsenides with various composition. The PGM are associated with sulfides as well as chromite and minor silicates. Grain-sizes are typically small (below 10 µm, usually c. 5 µm and smaller). Furthermore, feed, concentrate and tailings from the Thaba mine processing plant were investigated to estimate the mineralogical controls on the distribution of the PGM during chromite processing.
Keywords: -
  • Lecture (Conference)
    35th INTERNATIONAL GEOLOGICAL CONGRESS, 27.08.-04.09.2016, Kapstadt, Südafrika

Permalink: https://www.hzdr.de/publications/Publ-24624
Publ.-Id: 24624


Advanced discrimination of In-bearing minerals by automated mineralogy

Bachmann, K.; Frenzel, M.; Krause, J.; Gutzmer, J.
The identification and accurate characterization of discrete Indium minerals is usually a very cumbersome procedure due to their small grain size (typically below 10 μm) and complex mineral assemblage in massive sulfide mineralizations. A novel strategy for finding discrete In minerals and quantifying their composition was developed by using a mineral liberation analyzer (MLA) and an electron microprobe analysis (EPMA). The method was successfully applied to polymetallic massive sulfide ores with an incompletely known mineralogical composition from the Neves-Corvo deposit in Portugal. The occurrence of roquesite and sakuraiite could be systematically detected, their concentration quantified by MLA measurements, and their identity later confirmed by EPMA analyses. Based on the results obtained, an almost complete deportment of In was obtained for the six samples studied. This supports the approach taken, combining automated mineralogical data with electron microprobe analysis. A similar approach can be easily applied to other common minor and trace elements in complex base-metal sulfide ores, e.g. Se, Ge, Sb, or Ag, thus permitting targeted development of resource technologies suitable for by-product recovery.
Keywords: MLA, automated mineralogy, Indium, Neves Corvo, roquesite, sakuraiite

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Permalink: https://www.hzdr.de/publications/Publ-24623
Publ.-Id: 24623


Particle-based Sb distribution model for Cu–Pb flotation as part of geometallurgical modelling at the polymetallic Rockliden deposit, north-central Sweden

Minz, F. E.; Bolin, N.-J.; Lamberg, P.; Wanhainen, C.; Bachmann, K.; Gutzmer, J.
The polymetallic Cu–Zn ore of the Rockliden massive sulphide deposit in the Skellefte District in north-central Sweden contains a number of deleterious elements in relevant concentrations. Of particular concern is the amount of antimony (Sb) reporting to the Cu–Pb concentrate. The aim of this study was to compare different model options to simulate the distribution of Sb minerals in a laboratory flotation test based on different degrees of details in the mineralogical information of the flotation feed. Experimental data obtained from four composites were used for the modelling and simulation. The following different simulation levels were run (sorted from least to highest level of detail of their mineralogical information): chemical assays, unsized bulk mineralogy, sized bulk mineralogy and particle information. It was shown that recoveries simulated based on bulk mineralogy are mostly within the error margin acceptable in the exploration stage of the Rockliden deposit. Unexpected high deviation in the simulation using particle information from the original recovery has been partly attributed to the fact that recovery of non-liberated particles cannot be modelled appropriately in the present version of the modelling and simulation software. It is expected that the implementation of full particle information in simulation will improve the Sb distribution model for the mineralogically complex Rockliden deposit.
Keywords: Flotation kinetics, Mineral floatability, Modelling, Sulphide ores, Antimony, Liberation

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Permalink: https://www.hzdr.de/publications/Publ-24622
Publ.-Id: 24622


Lead, Zinc and their minor elements: enablers of a circular economy

Reuter, M. A.; Matusewicz, R.; van Schaik, A.
In their own right, both lead and zinc are crucial everyday metals playing their well-known roles in our society. Increasingly, they are linked in concert with the other base metals, copper, nickel and cobalt, which together form the crucial carrier metals for a sustainable society – the Web of Metals (WoM). This paper examines the special and crucial role both lead and zinc have in acting as enablers in any recycling efforts as they carry and release important and vital minor elements. Through examination of the rising needs for such carriers, this paper examines the approach and technologies which need to be considered by any producer of lead or zinc. Attention is paid to the limits and extent of this carrier role in the typical processing of materials. Examples of specialised technology and flow sheet needs are presented with consideration given to a “whole of chain” or systems-integrated metal production (SIMP) approach as a cornerstone of a circular economy. Also outlined are the challenges facing not only producers, but legislators who need to consider the balance between providing our societal needs with baseline technology infrastructure requirements for valuable metals extraction. A number of conclusions after each section summarize the message of this paper, which states simply that not only is the criticality of metals important but the criticality of the infrastructure (Infrastructure Criticality) that can recover metals from complex mixtures. Lead and zinc are metals at the heart of a Circular Economy, therefore key enablers of the Internet-of-Things (IoT).
Keywords: Resource efficiency – Lead – Zinc – Gallium – Indium – Antimony – Recycling – System integration – Design for Recycling (DfR)
  • World of Metallurgy - Erzmetall 68(2015)3, 132-146

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Permalink: https://www.hzdr.de/publications/Publ-24620
Publ.-Id: 24620


The role of temporal contrast for proton acceleration experiments at Draco

Obst, L.; Metzkes, J.; Zeil, K.; Schlenvoigt, H.; Kraft, S.; Rehwald, M.; Bock, S.; Helbig, U.; Gebhardt, R.; Schramm, U.
The role of temporal contrast and a possible diagnostics in the experimental area are presented.
Keywords: Laser, Plasma, Contrast, Proton Acceleration
  • Lecture (others)
    Draco Workshop, 19.12.2016, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24619
Publ.-Id: 24619


High-contrast laser-proton acceleration from condensed hydrogen jet and ultra-thin foils

Rehwald, M.; Zeil, K.; Obst, L.; Schlenvoigt, H.-P.; Brack, F.; Metzkes, J.; Kluge, T.; Kraft, S.; Sommer, P.; Loeser, M.; Ziegler, T.; Schramm, U.; Goede, S.; Wolter, S.; Kazak, L.; Gauthier, M.; Curry, C.; Macdonald, M.; Schumaker, W.; Mishra, R.; Ruyer, C.; Fiuza, F.; Roedel, C.; Glenzer, S.
Demanding applications like radiation therapy of cancer have pushed the development of laser plasma proton accelerators and defined levels of control and necessary proton beam stability in laser plasma experiments. The presentation will give an overview of the recent experiments for laser driven proton acceleration with high contrast at the high power laser Draco at HZDR, delivering pulses of 30fs and 5J. We present results of an experimental campaign employing a pure condensed hydrogen jet as a renewable target. The jet's nominal electron density is approximately 30 times the critical density and its diameter can be varied to be 2µm, 5µm or 10µm and thus allowing to study the regime of relativistic transparency. Different ion diagnostics reveal mono-species proton acceleration in the laser incidence plane around the wire-like target. Radiochromic film stacks in forward direction display signatures of filament-like structures, stemming from a Weibel-like instability generated at the rear side of the target in the underdense plasma region. A comparison of the data with results obtained using ultra-thin foils at high-contrast provided by a single plasma-mirror will be given.
Additionally, the expanding jet could be monitored on-shot with a temporally synchronized probe beam perpendicular to the pump laser axis. Recorded probe images resemble those of z-pinch experiments with metal wires and indicate sausage-like instability along the jet axis.
Keywords: Z-pinch, laser proton acceleration, cryogenic hydrogen jet, laser plasma
  • Lecture (Conference)
    34-th European Conference on Laser Interaction with Matter, 18.09.-23.12.2016, Moscow, Russia

Permalink: https://www.hzdr.de/publications/Publ-24618
Publ.-Id: 24618


Synthesis and in vitro evaluation of new fluorinated quinoline derivatives with high affinity for PDE5: Towards the development of new PET neuroimaging probes

Liu, J.; Maisonial-Besset, A.; Wenzel, B.; Canitrot, D.; Baufond, A.; Chezal, J. M.; Brust, P.; Moreau, E.
The increasing incidence of Alzheimer’s disease (AD) worlwide is a major public health problem. Current treatments provide only palliative solutions with significant side effects. Therefore, new efficient treatment options and novel early diagnosis tools are urgently needed. Recently, strong pre-clinical evidences suggested that phosphodiesterase 5 (PDE5) may be clinically relevant both as biomarker and drug-target in AD. In this study, we intended to develop a new radiofluorinated tracer for the visualisation of PDE5 in brain using PET imaging. Based on currently known PDE5 inhibitors, a series of novel fluorinated compounds bearing a quinoline core have been synthesised via multi-steps reaction pathways. Their affinity for PDE5 and selectivity over other PDE families have been investigated. According to the data collected from this in vitro screening, fluorinated derivatives 24a, b bearing a fluoroethoxy group at the C-3 position of the quinoline core appeared to be the most promising structures and will be further radiolabelled with fluorine-18 for in vitro and in vivo evaluations as PET radiotracer for neuroimaging of PDE5.

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Permalink: https://www.hzdr.de/publications/Publ-24617
Publ.-Id: 24617


A small animal tumour model for low-energy laser-accelerated particles

Pawelke, J.; Brüchner, K.; Krause, M.; Leßmann, E.; Schmidt, M.; Beyreuther, E.
no abstract available
Keywords: no keywords available
  • Open Access Logo Abstract in refereed journal
    Radiotherapy and Oncology 123(2017)Suppl. 1, S87-S87
    DOI: 10.1016/S0167-8140(17)30612-6
  • Invited lecture (Conferences)
    ESTRO 36, 05.-09.05.2017, Vienna, Austria

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Permalink: https://www.hzdr.de/publications/Publ-24616
Publ.-Id: 24616


Gold: A key enabler of a Circular Economy

Reuter, M. A.
This lecture discusses facetes of the book chapter below.

Metals are an essential and critical component of today's society: a moment's reflection on their ubiquitous presence in virtually all energy and material production processes is sufficient to confirm this. Metals play a key role in enabling sustainability through various high-tech applications in society. However, the resources of our planet are limited, as is the strain to which we can subject it in terms of emissions, pollution, and disposal of waste. For these reasons, finding ways to lower the environmental footprint of our collective existence and therefore lowering greenhouse gas and other emissions is a vital priority. The principal theme of this contribution is the maximization of resource efficiency as well as enabling a circular economy (CE) through the recycling of waste electric and electronic equipment, with a focus on precious metals (PMs) (incorporating gold, silver, and the platinum group metals [PGMs]) and the base-metal industry that enables their recycling. The detailed and deep knowledge that is required to systemically fully understand resource efficiency in the context of a CE are discussed and the concepts of design for resource efficiency and design for recycling elaborated on. Specifically, the understanding of product-centric recycling is highlighted, setting it apart from the usual material-centric recycling approaches. The latter focus more on bulk materials and therefore inherently limit the maximal recovery of technologically critical elements in particular, as well as PMs and PGMs. The base metals – principally, copper, cobalt, lead, nickel, tin, and zinc – all play a crucial part in the present society. Increasingly, these are linked in concert to form the crucial carrier metals for the sustainable CE society termed the “web of metals” and “web of products” or, in a more modern paradigm, system integrated metal production–in other words, the process metallurgical Internet of things. This chapter also examines the special and crucial role base metals have in acting as enablers in any recycling efforts, as they also play a key role during recycling, such as copper and lead being the solvent of gold and other PMs and PGMs and release them during refining. Above all, the PMs are key economic enablers for the economic viability of recycling as well as the metallurgical infrastructure (system integrated metal production/Internet of things) that makes it possible to recover PMs and PGMs and their other associated elements.
Keywords: Critical metals; Design for recycling; Furnace technology; Gold; Hydrometallurgy; Internet-of-things; Precious metals; Process metallurgy; Pyrometallurgy; Recycling; System integrated Metal production; WEEE
  • Invited lecture (Conferences)
    World Gold Conference, 29.09.-01.10.2015, Johannesburg, South Africa

Permalink: https://www.hzdr.de/publications/Publ-24615
Publ.-Id: 24615


Resource efficiency and circular economy - understanding the concepts

Reuter, M. A.
This lecture discusses facetes of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    Global Network Conference on Resource Efficient and Cleaner Production, 12.-16.10.2015, Davos, Switzerland

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Permalink: https://www.hzdr.de/publications/Publ-24614
Publ.-Id: 24614


Metallurgical restrictions for WEEE recycling – consequences for the product design

Reuter, M. A.
This lecture discusses facets of the article below.

Metals are an essential and critical component of today’s society: a moment’s reflection on their ubiquitous presence in virtually all energy and material production processes is enough to confirm this. Metals play a key role in Enabling Sustainability through societies various high-tech applications. However, the resources of our planet are limited, as is the strain to which we can subject it in terms of emissions, pollution, and disposal of waste. For these reasons, finding ways to lower the environmental footprint of our collective existence and therefore lowering greenhouse gas emissions and help mitigate climate change is a vital priority ([1], [2]). The maximization of resource efficiency [3] is the principal theme of this contribution. It will be shown in depth the detail that is required to systemically fully understand resource efficiency in the context of material use, illustrating this by example of E-waste recycling. The opportunities and limits of recycling are discussed with a specific emphasis on the physics and related economics of recycling. Through this Design for Resource Efficiency is elaborated on. In support of this, the detailed data that are required, the technological understanding and design rules are among others implicitly highlighted that impact on resource efficiency. Specifically the understanding of Product-Centric recycling is highlighted setting it apart from the usual Material-Centric recycling approaches (which focus more on bulk materials) and therefore inherently limit especially the maximal recovery of technologically critical elements - these limitations will be discussed.
  • Invited lecture (Conferences)
    Resources from Waste: Sorting and Treatment Techniques / ISWA Beacon Conference 2015, 14.-16.10.2015, Hamburg, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-24613
Publ.-Id: 24613


Thermoacoustic MHD generator prototyping and experiments

Brekis, A.; Freibergs, J.; Gailitis, A.; Roy, E.; Jeantet, P.; Poli, G.; Zeminiani, E.; Francoism, M.-X.; Gerbeth, G.; Eckert, S.
This paper describes a machine based on coupled thermo acoustic (TAc) and magnetohydrodynamic (MHD) generators, which are an innovating technology ideally free of moving parts. In Europe there is a strong expertise in thermo acoustic and MHD. But these technologies have never been coupled. Both engines have been manufactured and tested in Institute of Physics of University of Latvia (IPUL). At first MHD generator and TAc generator were tested separately and then both together. The aim of these tests was a validation of possibility of making sodium oscillations with external force, testing free surface stability of gas-liquid sodium and studying of TAc generator working principles in different conditions.
Keywords: MHD generator; thermo acoustic
  • Contribution to proceedings
    10. PAMIR International Conference, 20.-24.06.2016, Cagliari, Italien, 606-610

Permalink: https://www.hzdr.de/publications/Publ-24612
Publ.-Id: 24612


Focused Helium and Neon Ion Beam Modification of High-Tc Superconductors and Magnetic Materials

Cybart, S. A.; Bali, R.; Hlawacek, G.; Röder, F.; Fassbender, J.ORC
The ability of gas field ion sources (GFIS) to produce controllable inert gas ion beams with atomic level precision opens up new applications in nanoscale direct-write material modification. Two areas where this has recently been demonstrated is focused helium ion beam production of high-transition temperature (high-TC) superconductor electronics and magnetic spin transport devices. The enabling advance in the case of superconducting electronics is the ability to use the GFIS to make features on the small length-scale of quantum mechanical tunnel barriers. Because the tunneling probability depends exponentially on distance, tunnel barriers must be less than a few nanometers wide, which is beyond the limits of other nanofabrication techniques such as electron beam lithography. In magnetism, the GFIS has recently been used to generate chemical disordering and modify magnetic properties at the nanoscale. The strongest effect is observed in materials where ion-induced chemical disordering leads to increased saturation magnetization, enabling positive magnetic patterning. In this chapter, we review the latest results and progress in GFIS ion beam modification of (high-TC) superconductors and magnetic materials.
Keywords: GFIS-assisted modifications, superconductivity, magnetism
  • Book chapter
    Hlawacek, Gregor, Gölzhäuser, Armin: NanoScience and Technology, Heidelberg: Springer-Verlag GmbH, 2016, 978-3-319-41990-9, 415-445
    DOI: 10.1007/978-3-319-41990-9_17
  • Lecture (Conference)
    International Conference on Surface Modification of Materials by Ion Beams (SMMIB-2017), 09.-14.07.2017, Lisboa, Portugal
  • Lecture (Conference)
    International Baltic Conference on Magnetism 2017, 20.-24.08.2017, Kaliningrad, Russia

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Permalink: https://www.hzdr.de/publications/Publ-24611
Publ.-Id: 24611


Measuring liquid flow in structured packings using gamma and x-ray tomography

Hoffmann, R.; Boden, S.; Schubert, M.; Hampel, U.
Detailed knowledge of the liquid distribution in structured packings is an essential requirement for developing high-performance columns. Two different tomographic technologies are used to resolve the liquid distribution on different length scales. A variety of hydrocarbons, silicone oil and water can be used as model fluids.

For macroscopic measurements of the whole column cross-section (up to Ø 750 mm) a gamma tomograph has been built. The tomograph is qualified to operate in ATEX areas and can resolve liquid flow phenomena like wall flow, inlet flow distribution, crossover between packing blocks etc.

For microscopic measurements of flow details x-ray tomography is used. Using a voxel size of 41 μm the influence of the packing's geometry parameters on the liquid flow can be analyzed. The resulting data is also used for verification of corresponding two-phase flow CFD simulations.
Keywords: Structured packings, gamma tomography, x-ray tomography
  • Contribution to proceedings
    International Conference on Multiphase Flow, ICMF 2016, 22.-27.05.2016, Firenze, Italy
    ICMF2016 Proceedings
  • Lecture (Conference)
    International Conference on Multiphase Flow, ICMF 2016, 22.-27.05.2016, Firenze, Italy

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Permalink: https://www.hzdr.de/publications/Publ-24610
Publ.-Id: 24610


Raw materials demand in a circular, low-carbon economy

Reuter, M. A.
This lecture discusses facetes of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    4th annual High-Level Conference of the European Innovation Partnership on Raw Materials / Raw Materials Week, 28.11.-02.12.2016, Brüssel, Belgien

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Permalink: https://www.hzdr.de/publications/Publ-24609
Publ.-Id: 24609


Perspektiven einer Entsorgungsindustrie und Kreislaufwirtschaft 4.0

Reuter, M. A.
This lecture discusses facetes of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    Industrie 4.0. - Chancen und Risiken für die Umwelt, 18.11.2016, Dessau-Roßlau, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-24608
Publ.-Id: 24608


Short-pulse laser-driven x-ray radiography

Brambrink, E.; Baton, S.; Koenig, M.; Yurchak, R.; Bidaut, N.; Albertazzi, B.; Cross, J. E.; Gregori, G.; Rigby, A.; Falize, E.; Pelka, A.; Kroll, F.; Pikuz, S.; Sakawa, Y.; Ozaki, N.; Kuranz, C.; Manuel, M.; Li, C.; Tzeferacos, P.; Lamb, D.
We have developed a new radiography setup with a short-pulse laser-driven x-ray source. Using a radiography axis perpendicular to both long- and short-pulse lasers allowed optimizing the incident angle of the short-pulse laser on the x-ray source target. The setup has been tested with various x-ray source target materials and different laser wavelengths. Signal to noise ratios are presented as well as achieved spatial resolutions. The high quality of our technique is illustrated on a plasma flow radiograph obtained during a laboratory astrophysics experiment on POLARs.
Keywords: laboratory astrophysics; short-pulse laser; x-ray radiography

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Permalink: https://www.hzdr.de/publications/Publ-24607
Publ.-Id: 24607


Dispersion of nanaoparticles in metals using pulsed electromagnetic interaction

Bojarevics, A.; Kaldre, I.; Beinerts, T.; Grants, I.; Milgravis, M. M.; Kalvans, M.
This research work is done to investigate the possibilities how to mix and disperse ceramic nanoparticles in liquid metals and keep them dispersed during solidification. We investigate contactless electromagnetic methods to produce metal matrix nano-composites. Dispersed particles improves mechanical and thermal properties of the metals by refining metallic grains and limiting crack propagation. We use intensive electromagnetic interaction from capacitor bank discharge to create pressure oscillations liquid metal which induces acoustic cavitation which then causes intensive micro-scale jet which is able to break particle agglomerates.
Keywords: liquid metals
  • Contribution to proceedings
    10. PAMIR International Conference, 20.-24.07.2016, Cagliari, Italy, 266-361

Permalink: https://www.hzdr.de/publications/Publ-24606
Publ.-Id: 24606


Analytical solution for the diffusion of a capacitor discharge generated magnetic field pulse in an conductor

Grants, I.; Bojarevics, A.; Gerbeth, G.
Powerful forces arise when a pulse of a magnetic field in the order of a few tesla diffuses into a conductor. Such pulses are used in electromagnetic forming, impact welding of dissimilar materials and grain refinement of solidifying alloys. Strong magnetic field pulses are generated by the discharge current of a capacitor bank. We consider analytically the penetration of such pulse into a conducting half-space. Besides the exact solution we obtain two simple self-similar approximate solutions for two sequential stages of the initial transient. Furthermore, a general solution is provided for the external field given as a power series of time. Each term of this solution represents a self-similar function for which we obtain an explicit expression. The validity range of various approximate analytical solutions is evaluated by comparison to the exact solution.
Keywords: magnetic field

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Permalink: https://www.hzdr.de/publications/Publ-24605
Publ.-Id: 24605


Herausforderungen bei der bruchmechanischen Prüfung von oxiddispersionsverfestigten (ODS)-Cr-Stählen

Viehrig, H.-W.; Das, A.; Houska, M.; Hoffmann, J.
Different oriented 0.25T- and 0.16T-C(T) specimens of hot rolled- and hot extruded 14Cr ODS steel were tested within the temperature range from 20°C to 700°C. Elastic-plastic fracture toughness values were estimated according to ASTM E1820 15 on J-∆a curves measured by the unloading compliance method. The rolled plate of 13Cr ODS had higher fracture toughness in L-T than in T-L orientation. The rolled ODS shows secondary cracks which were more pronounced for the L-T oriented C(T) specimens than for T-L orientation. The secondary cracks strongly influence the propagation of the main crack. The fracture toughness of the hot extruded 14 Cr ODS also strongly depend on the specimen orientation.
Keywords: ODS steel, temperature, C(T) specimen, crack extension curve, unloading compliance, fracture toughness
  • Contribution to proceedings
    49. Tagung des DVM Arbeitskreises Bruchmechanik und Bauteilsicherheit Bruchmechanische Werkstoff- und Bauteilbewertung: Beanspruchungsanalyse, Prüfmethoden und Anwendungen, 14.-15.02.2017, Mittweida, Deutschland, Berlin: DVM

Permalink: https://www.hzdr.de/publications/Publ-24604
Publ.-Id: 24604


Geometallurgie als integrative Prozessoptimierung

Reuter, M. A.
Prof. Dr. Dr. h.c. Markus Reuter stellte in seinem Vortrag eine durchgeführte Bewertung der Ressourceneffizienz am Beispiel von LED-Lampen vor. In der Vorgehensweise wurden verschiedene Konstruktionen sowie Materialzusammensetzung untersucht und simuliert. Prof. Reuter betonte dabei, dass für den Vergleich komplexer Produkte auch komplexe Simulationen notwendig seien. Durch Simulationen unter Berücksichtigung des gesamten Lebenszyklus ließen sich bereits in der Entwicklungsphase von Produkten Konstruktion und Materialauswahl hinsichtlich der Recyclingfähigkeit optimieren. Da aufgrund technischer und chemischer Einschränkungen nicht alle Bestandteile vollständig zurückgewonnen werden könnten, sei eine Betrachtung von Recyclingprozessen auf metallurgischer Ebene notwendig, um ein ressourceneffizientes Recycling zu realisieren.
  • Invited lecture (Conferences)
    Produktentwicklung als Hebel für Ressourceneffizienz – Potenziale im Dialog zwischen Politik, produzierenden Unternehmen und Recyclingwirtschaft / 18. NeRess-Konferenz, 05.12.2016, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24603
Publ.-Id: 24603


Geochemical analysis of the European Kupferschiefer – from method development to data assessment

Rahfeld, A.; Wiehl, N.; Möckel, R.; Gutzmer, J.
The European Kupferschiefer is currently the world’s most important source of Ag and an important source of Cu, Au, Mo, Ni, Pb, Se and Re. Cu is the main product, with grades of 2.5 wt% Cu and 62 ppm Ag on average. The Kupferschiefer sensu strictu is a very fine-grained, finely laminated and fissile carbonaceous shale. Complex sulphide mineralogy, a great variety of clay minerals and very high organic carbon contents render mineralogical as well as geochemical characterization of the Cu-rich Kupferschiefer difficult. The availability of high quality whole rock geochemical data sets in the published literature is strictly limited. A detailed geochemical study was thus undertaken within the framework of the Ecometals project [1]. Within the context of this study, different analytical methods were compared and a suitable approach for a routine analytical protocol developed.

X-ray fluorescence (XRF) and inductively coupled plasma optical emission spectrometry (ICP-OES) were tested as potential techniques based on their availability and adaptability to analyse main (Al, Ca, Cu, Fe, K, Mg, Pb, Si, Zn) and trace (Ag, As, Ba, Co, Mo, Ni, Ti, V) element concentrations. It is known that both techniques can be susceptible to errors either caused by matrix effects in the material itself, sample preparation or interferences. To ascertain the accuracy of XRF and ICP-OES analysis, instrumental neutron activation analysis (INAA) was carried out at the TRIGA research reactor in Mainz.

Two approaches were tested in the digestion process for this material. Especially the organic carbon in the samples is known to be resistant, which is why Na-peroxide digestion within an HCl solution was used in addition to classic acid digestion based on HF and HNO3. The ICP-OES results show great accordance to the ones measured by INAA for both acid and peroxide digestion, although a complete digestion was only achieved by peroxide digestion and is reflected in slightly increased Cu concentrations.

Further information needs to be taken into consideration when working with XRF pressed pellets. To process the data correctly, knowledge about the mineralogical composition is necessary to distinguish between oxide and sulphide compounds. The total organic carbon content (TOC) needs to be determined independently and used to correct the XRF data. A preceding calcination of the material can not be recommended and should be approached with caution. The copper sulphides start sintering at temperatures above 780°C and ruin any crucible.

In accordance with the results, both acid and peroxide digestion with subsequent ICP-OES analysis can be recommended for the analysis of Kupferschiefer. Whilst ICP-OES measurements and the sample preparation through digestion are more time consuming compared to the ones used for XRF, the data quality is better and there is no explicit requirement for additional TOC data, mineralogical measurements or data correction.
  • Lecture (Conference)
    International Geological Congress, 28.08.-02.09.2016, Cape Town, South Africa

Permalink: https://www.hzdr.de/publications/Publ-24602
Publ.-Id: 24602


Organische Chemie VI - Stoffklassen und funktionelle Gruppen V

Mamat, C.
Im letzten Studienheft des großen ersten Abschnittes der organischen Chemie wollen wir uns mit wichtigen Stoffklassen beschäftigen, die auch in Molekülen aus der Natur vorhanden sind. Sie werden staunen, dass die funktionellen Gruppen, die wir uns bisher angeschaut haben, zu einem Großteil in diesen biologisch aktiven Molekülen wiederzufinden sind. Zwei große Klassen von Biomolekülen stehen da im Vordergrund: die Kohlenhydrate und die Aminosäuren bzw. deren makromolekulare Kondensationsverbindungen, die Peptide und Proteine. Ausgehend davon werden wir noch einen Blick auf die Heterocyclen werfen, da sie ebenfalls in einer Vielzahl von Biomolekülen und auch pharmazeutischen Produkten und Verbindungen vorkommen und damit eine große Rolle als Wirkstoffe in der Biochemie spielen.
  • Book (Authorship)
    Heidelberg: Springer Verlag, 2016
    0034 Seiten

Permalink: https://www.hzdr.de/publications/Publ-24601
Publ.-Id: 24601


Organische Chemie V - Stoffklassen und funktionelle Gruppen IV

Mamat, C.
Im 4. Studienheft haben wir wichtige Reaktionen rund um die Carbonylgruppe kennengelernt. Generell beginnen alle Reaktionen immer mit einem nucleophilen Angriff auf das sp2-hybridisierte und elektrophile Carbonyl-C-Atom unter Ausbildung eines sp3-hybridiserten C-Atoms. Die Hybridisierung des C-Atoms bleibt erhalten (Reduktion, Hydrierung, Acetalisierung) oder sie wird wieder zurückgebildet zu sp2, wie bei Veresterungen oder Amidierungen im Sinne eines Additions-Eliminierungs-Mechanismus. Dieser Austausch am Carbonyl-C-Atom unterscheidet sich mechanistisch jedoch grundlegend von den SN-Reaktionen am gesättigten (sp3) C-Atom. Bitte beachten Sie das!
Des Weiteren haben wir ausgearbeitet, dass die α-Position (also die Position in Nachbarschaft der C=O-Gruppe) der Ketone und Aldehyde eine ganz besondere Reaktivität besitzt, im Vergleich zu den restlichen C-Atomen der organischen Substituenten an der C=O-Gruppe.
Genau an dieser Stelle wollen wir ansetzen und weitere wichtige Reaktionen und damit verbundene Stoffklassen kennenlernen, die auch mehr als eine funktionelle Gruppe tragen.
  • Book (Authorship)
    Heidelberg: Springer Verlag, 2016
    0032 Seiten

Permalink: https://www.hzdr.de/publications/Publ-24600
Publ.-Id: 24600


Organische Chemie IV - Stoffklassen und funktionelle Gruppen III

Mamat, C.
Im letzen Heft haben wir gelernt, welche Reaktionen an nicht-aktivierten (einfachen) Doppelbindungen durchgeführt werden und welche Verbindungen daraus entstehen. In diesem Heft wollen wir schauen, was für Reaktionen möglich sind, wenn die Doppelbindung aus einem Kohlenstoffatom und einem Heteroatom (in der Hauptsache: Sauerstoff) besteht. Die Grundlagen dieser aktivierten Doppelbindungen dem 1. Studienheft wollen wir jetzt erweitern und schauen wie der gebildete Dipol die Reaktivität und Reaktionen an diesen Doppelbindungen beeinflusst. Wir suchen Analogien und Unterschiede zu den Reaktionen am gesättigten C-Atom und wollen sehen, wie wir zu solchen ungesättigten Systemen ausgehend aus den gesättigten kommen. Daraus ergeben sich weitere, neue funktionelle Gruppen und Substanzklassen, die wir ebenfalls beleuchten wollen.
  • Book (Authorship)
    Heidelberg: Springer Verlag, 2016
    0034 Seiten

Permalink: https://www.hzdr.de/publications/Publ-24599
Publ.-Id: 24599


Organische Chemie III - Stoffklassen und funktionelle Gruppen II

Mamat, C.
Die einfachen Kohlenwasserstoffe haben wir im letzten Heft kennengelernt, und auch welche generelle Reaktionen am gesättigten C-Atom möglich sind. Dabei sind wir auf die große Gruppe der Halogenalkane gestoßen und haben deren Eigenschaften und Reaktionen angeschaut und ebenfalls die Eigenschaften und Grundreaktionen mit ungesättigten Verbindungen ohne Heteroatom. Wir haben auch gesehen, dass Heteroatome in Abhängigkeit von ihrer Elektronegativität zur Polarisierung der Bindung beitragen. Somit kann diese heterolytisch gespalten werden. Unter dieser Voraussetzung sind nucleophile Substitutionen an diesem Kohlenstoffatom möglich, aber auch Eliminierungsreaktionen zur Erzeugung von Mehrfachbindungen.
In diesem Heft wollen wir uns speziell mit Stoffeigenschaften der Alkohole, Ether, Thioalkohole, Thioether und Amine beschäftigen und wie wir diese Verbindungen generell synthetisieren bzw. diese funktionellen Gruppen erhalten können. Die Grundlage für dieses Heft bilden die zuvor besprochenen nucleophilen Substitutionsreaktionen. Des Weiteren werden wir sehen, welche Nebenreaktionen bei der Synthese dieser Verbindungsklassen auftreten und unter welchen Bedingungen sie verhindert oder begünstigt werden können.
  • Book (Authorship)
    Heidelberg: Springer Verlag, 2016
    0030 Seiten

Permalink: https://www.hzdr.de/publications/Publ-24598
Publ.-Id: 24598


Organische Chemie II, Stoffklassen und funktionelle Gruppen I

Mamat, C.
Ab jetzt geht es in die Tiefe. Nach den allgemeinen Grundlagen und Informationen rund um den Kohlenstoff wollen wir uns im zweiten Heft ausführlich mit den einfachen Kohlenwasserstoffen und deren Reaktionsmöglichkeiten auseinandersetzen und schauen, was es mit Doppel- und Dreifachbindungen auf sich hat. Dann werfen wir einen Blick auf die Auswirkungen auf Reaktionen, insbesondere wenn Halogene am Kohlenstoff gebunden sind. Wir werden sehen, welche generellen Möglichkeiten es für Reaktionen am gesättigten Kohlenstoffatom gibt. Neben diesen Austausch- bzw. Substitutionsreaktionen lassen sich aus Halogenalkanen oder Alkoholen auch Eliminierungen durchführen unter Abspaltung von kleinen Molekülen und unter Bildung von Alkenen und Alkinen, wodurch ungesättigte Derivate entstehen. Welche Auswirkungen die Doppel- und Dreifachbindungen auf den Kohlenstoff und auf seine Reaktionen haben, besonders wenn elektronegative Atome in Nachbarschaft zu dieser Mehrfachbindung stehen, sehen wir uns an. Aromaten sind die letzte Stoffklasse in diesem Heft. Auf deren Eigenschaften und besondere Reaktionen im Vergleich zu den nichtaromatischen und/oder acyclischen Kohlenwasserstoffen gehen wir ebenfalls ein.
  • Book (Authorship)
    Heidelberg: Springer-Verlag, 2016
    0034 Seiten

Permalink: https://www.hzdr.de/publications/Publ-24597
Publ.-Id: 24597


Two-dimensional oscillations in MHD Rayleigh-Benard convection

Tasaka, Y.; Fujita, K.; Yanagisawa, T.; Vogt, T.; Sakuraba, A.; Eckert, S.
Short-period oscillations on convection rolls in Rayleigh-Bénard convection affected by a horizontal magnetic field confined in moderate aspect ratio box were invested experimentally. Detailed measurements of temperature and velocity fluctuations corresponding to the oscillations elucidated that the oscillation around its onset is two dimensional and may be originated in absolute instability of recirculation vortices formed flow separations due to large inertia of the main convection rolls restricted by Lorenz force.
Keywords: Rayleigh-Benard convection, liquid metal, magnetic field, flow measurements, ultrasound Doppler method
  • Lecture (Conference)
    24th International Congressof Theoretical and Applied Mechanics, 21.-26.08.2016, Montreal, Canada

Permalink: https://www.hzdr.de/publications/Publ-24596
Publ.-Id: 24596


Recycling’s Opportunities and Limits for a Circular Economy

Reuter, M. A.
This lecture discusses facetes of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    Opportunities and Limits of Recycling / Recycling Valley Innovative Reverse Metallurgy in Wallonia and in Europe, 21.11.2016, Liège, Belgium
  • Invited lecture (Conferences)
    Recycling von Edel- und Sondermetallen voranbringen / UBA-Workshop, 02.11.2015, Berlin, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-24595
Publ.-Id: 24595


Measurements of a three-dimensional flow in a cube by means of an ultrasound array Doppler velocimeter (UADV)

Nauber, R.; Galindo, V.; Franke, S.; Räbiger, D.; Büttner, L.; Thieme, N.; Beyer, H.; Czarske, J.; Eckert, S.
Velocity measurements were carried out in a cube filled with the liquid metal GaInSn using a dual plane, two-component ultrasound array Doppler velocimeter. The liquid metal was suddenly exposed to an azimuthal body force generated by a rotating magnetic field (RMF). The measurements show a similar flow structure compared to the case of the RMF-driven flow in a cylindrical container, in particular the so-called initial adjustment phase followed by an inertial phase which is dominated by inertial oscillations of the secondary flow. The interest was especially focused on the onset of unsteady flow regimes. The transition from the steady double vortex structure of the secondary flow to an oscillating regime was detected at a magnetic Taylor number of Ta > 1.3  105. A detailed analysis of the flow structure was done by means of the Proper Orthogonal Decomposition (POD). Corresponding numerical simulations were performed showing an excellent agreement with the experimental data.
Keywords: Flow measurements, liquid metal, Ultrasound Doppler method, sensor array, rotating magnetic field
  • Lecture (Conference)
    10th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering, 28.-30.09.2016, Tokyo, Japan
  • Contribution to proceedings
    10th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering, 28.-30.09.2016, Tokyo, Japan

Permalink: https://www.hzdr.de/publications/Publ-24594
Publ.-Id: 24594


Circular Economy: New wording or Real Policy?

Reuter, M. A.
This lecture discusses facets of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions. The author stands humbly on the shoulders of these developments and their distinguished developers. This award lecture article implicitly also refers to work done while working for Ausmelt (Australia), Outotec (Finland and Australia), Mintek (South Africa), and Anglo American Corporation (South Africa), honoring the many colleagues the author has worked with over the years.
  • Invited lecture (Conferences)
    Resourcing the Future / Beacon Conference on Waste Minimisation and Recycling, 15.-17.06.2016, Oslo, Norway

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Permalink: https://www.hzdr.de/publications/Publ-24593
Publ.-Id: 24593


Metallurgy a key enabler of a Circular Economy Challenges & Developments

Reuter, M. A.
This lecture discusses facets of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    Metallische Rohstoffe in der Zukunft - Prozessvisionen für Ressourceneffizienz / 55. Tutzing-Symposion 2016, 06.-07.06.2016, Tutzing, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-24592
Publ.-Id: 24592


Aufbereitung und Recycling – Schlüsselfaktoren der Gewinnung primärer und sekundärer Rohstoffe – Herausforderungen und Entwicklungen

Reuter, M. A.
This lecture discusses facets of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    Die Zukunft beginnt mit dem Rohstoff – Herausforderungen für die internationale Rohstoffwirtschaft / 10. Sächsischer Rohstofftag, 25.05.2016, Dresden, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-24591
Publ.-Id: 24591


Öffentliche Abendvorträge - "Wir kommen wieder!"

Merchel, S.; für die Veranstalter
Naturwissenschaftliche Einsichten in Kunst- und Kulturgut
Keywords: Archäometrie
  • Mitteilungsblatt der Fachgruppe Analytische Chemie der Gesellschaft Deutscher Chemiker (2016)04, 14-15

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Permalink: https://www.hzdr.de/publications/Publ-24590
Publ.-Id: 24590


Fragmentation-driven grain refinement in directional solidification of AlCu10wt-% alloy at low pulling speeds

Zimmermann, G.; Pickmann, C.; Hamacher, M.; Schaberger-Zimmermann, E.; Neumann-Heyme, H.; Eckert, K.; Eckert, S.
The formation of the grain structure in Al-10wt%Cu alloy during directional solidification was investigated experimentally. The alloy composition was chosen because of its special feature that both the initial melt composition and the solidifying primary Al dendrites have almost identical densities. Therefore, gravity-related effects such as buoyancy or sedimentation acting on nucleated or fragmented solid particles in the melt are expected to be minor. In 3D bulk samples at low solidification velocities, unexpected equiaxed grain growth was found instead of columnar growth. This behavior was investigated in accompanying solidification experiments with thin samples using in-situ X-ray diagnostics. It is demonstrated that fragments detach from the dendrite tip region and move slightly ahead of the solid-liquid interface as they grow. As a result, a dendritic microstructure consisting of elongated equiaxed grains is developed. Accordingly, fragmentation was identified as responsible for grain refinement in the given parameter range.
Keywords: solidification, fragmentation, grain refinement, X-ray radiography

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Permalink: https://www.hzdr.de/publications/Publ-24589
Publ.-Id: 24589


A generalized multi-field two-fluid concept for numerical simulation of two-phase flows

Oertel, R.; Lucas, D.; Schlegel, F.
Multiphase flows occur in a variety of industrial applications, e.g. in chemical engineering or in nuclear research. An important feature of these flows is the formation of different flow patterns depending on the relative flow rates of the phases. These patterns are not explicitly defined by the and have different characteristics. Past research on the simulation of multiphase flows mainly focused on establishing methods that are appropriate within a well-defined flow regime. The present contribution aims at the development of a generalized framework in OpenFOAM for the simulation of industrial scale multiphase flows with largely varying interfacial length scales, which has the capability to reproduce the mechanisms of flow pattern transitions. For the simulation of disperse flows, the two-fluid approach, where each phase is represented by its own phase-averaged velocity field, is widely accepted. This concept serves as a basis and is extended to allow interface-resolving simulations for large gas structures, while disperse phase elements are still represented in terms of a number density function. The present contribution focuses on two parts. Firstly, one feature of multiphase flow pattern transitions is the inherent polydispersity of the occurring gas structures. The difference in diameter between the smallest and the largest elements spans over at least one order of magnitude. In general, this aspect is taken into account by population balance modeling. A successful and stable method for this purpose is the method of classes which will be utilized here, following the ideas of the GENTOP-approach of Hänsch et al. (2012). Since lift-force induced separation of bubbles according to their size is considered as an important mechanism for the transition from bubbly to slug flow, particular emphasis is put on employing a class method which also takes different velocity fields for the disperse phase into account. The second part focuses on the handling of interface-resolving gas structures within the two-fluid model. Beside the aspect of interface sharpening to counteract the numerical diffusion, the momentum exchange between the separate velocity fields is important. In reality, the phases share a single velocity field and a no-slip condition is present at the interface. This condition can also be met in a two-fluid model by forcing the velocity of the two phases to be equal at interface. However, as such a method requires a high grid resolution, we introduce a direction depended model for the momentum exchange at the interface, that accounts separately for pressure and friction induced drag. Finally, the presented framework allows the simulation of multiphase flow problems close to an industrial scale and gives realistic predictions, even on a coarse grid.
  • Lecture (Conference)
    4th OpenFOAM User Conference 2016, 11.-13.10.2016, Köln, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24588
Publ.-Id: 24588


Electrically Tunable Nd:YAG waveguide laser based on Graphene

Ma, L.; Tan, Y.; Akhmadaliev, S.; Zhou, S.; Chen, F.
We demonstrate a tunable hybrid Graphene-Nd:YAG cladding waveguide laser exploiting the electrooptic and the Joule heating effects of Graphene. A cladding Nd:YAG waveguide was fabricated by the ion irradiation. The multi-layer graphene were transferred onto the waveguide surface as the saturable absorber to get the Q-switched pulsed laser oscillation in the waveguide. Composing with appropriate electrodes, graphene based capacitance and heater were formed on the surface of the Nd:YAG waveguide. Through electrical control of graphene, the state of the hybrid waveguide laser was turned on or off. And the laser operation of the hybrid waveguide was electrically tuned between the continuous wave laser and the nanosecond pulsed laser.

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Permalink: https://www.hzdr.de/publications/Publ-24587
Publ.-Id: 24587


INTRA r³+ - Integration und Transfer der r³ Fördermaßnahme

Dürkoop, A.; Büttner, P.; Albrecht, S.; Brandstetter, C. P.; Erdmann, M.; Gräbe, G.; Moller, B.; Höck, M.; Kleeberg, K.; Rentsch, L.; Schneider, K.; Ostertag, K.; Pfaff, M.; Sartorius, C.; Tercero Espinoza, L.; Szurlies, M.; Wilken, H.
Die r³ Fördermaßnahme wurde von Ende 2011 bis Anfang 2016 durch das Bundesministerium für Bildung und Forschung (BMBF) mit 30 Mio. € gefördert. Zusätzlich wurden 12 Mio. € Industriemittel in den r³ Verbundprojekten eingesetzt. Die insgesamt 28 r³ Verbundprojekte forschten daran, wie nicht-energetische mineralische Rohstoffe zukünftig effizienter genutzt werden können (Bild 1). Bundesweit waren mehr als 120 Partner in r³ eingebunden, darunter zahlreiche Forschungseinrichtungen und Behörden sowie 69 Industrieunternehmen. Der Fokus von r³ lag auf den für Deutschland wirtschaftsstrategisch wichtigen Metallen [BMBF 2012] wie z.B. Indium, Germanium, Gallium und seltene Erden (SEE), aber auch Industrieminerale wie beispielsweise Flussspat, die zukünftig effizienter gewonnen, recycelt und in Produkten verwendet werden sollen. Diese strategischen Metalle und Mineralien werden vor allem für die Herstellung von Hightech-Produkten (Handys, Laptops, Touchscreens, LCDs usw.) und Energiesparlampen, aber auch für Dauermagnete benötigt.
Wenn auch die metallischen Ressourcen nicht in großen Mengen verwendet werden, so sind sie doch wirtschaftsstrategisch von großer Bedeutung [BMBF 2010]. Eine unsichere Versorgungslage für diese strategischen Rohstoffe in Deutschland könnte zu Versorgungsengpässen im Rohstoffimportland Deutschland führen. Die Ergebnisse aus r³ zeigen, dass die Versorgungslage für einige dieser Rohstoffe für Deutschland zukünftig verbessert werden könnte.
Die Bewertung der Ergebnisse aus r³ erfolgte im Rahmen des Projekts INTRA r³+ (Bild 2) unter Leitung des Helmholtz-Instituts Freiberg für Ressourcentechnologie (HIF). Zur Bewertung der Nachhaltigkeit der r³ Ergebnisse wurden zum einen ökonomisch-ökologisch-soziale Aspekte analysiert und zum anderen gesamtwirtschaftliche Betrachtungen durchgeführt sowie die Versorgungssicherheit bewertet. Zudem wurde die Vernetzung der r³ Verbundprojekte untereinander aber auch mit externen Initiativen und Projekten mit diversen Maßnahmen angeregt. Darüber hinaus wurden Arbeiten und Ergebnisse öffentlichkeitswirksam publiziert und ein Technologietransfer in die Wirtschaft vorbereitet. Partner von INTRA r3+ sind neben dem HIF die Technische Universität Bergakademie Freiberg (TUBAF), die Abteilung Ganzheitliche Bilanzierung des Lehrstuhls für Bauphysik (LBP) der Universität Stuttgart, das Fraunhofer Institut für System- und Innovationsforschung (ISI), das Fraunhofer-Institut für Chemische Technologie (ICT) und die Deutsche Rohstoffagentur (BGR/DERA).
Keywords: Ressourcentechnologie, Nachhaltigkeit, strategische Metalle
  • Open Access Logo Book chapter
    A. Dürkoop, C. P. Brandstetter, G. Gräbe, L. Rentsch: Innovative Technologien für Ressourceneffizienz - Strategische Metalle und Mineralien, Stuttgart: Fraunhofer Verlag, 2016, 978-3-8396-1102-9

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Permalink: https://www.hzdr.de/publications/Publ-24585
Publ.-Id: 24585


Non-ferrous metallurgy: Key enabler of a circular economy

Reuter, M. A.
Base metals such as copper, lead, nickel, cobalt, zinc etc. form the basic crucial carrier metals for a sustainable society – the Web of Metals. The lecture discusses the special and crucial role these metals have in acting as enablers in any recycling efforts as they carry and release important and vital minor elements at the heart of high-tech applications and products. Through examination of the rising needs for such carriers, this lecture examines the approach and technologies which need to be considered by any producer of base metals. Attention is paid to the limits and extent of this carrier role in the typical processing of materials.
Examples of specialised technology and flowsheet needs are presented with consideration given to a “whole of chain” or Systems-Integrated Metal Production (SIMP) approach as a cornerstone of a circular economy. Also outlined are the challenges facing not only producers, but legislators who need to consider the balance between providing our societal needs with baseline technology infrastructure requirements for valuable metals extraction. In summary, the message of this paper states simply that not only is the criticality of metals important but the criticality of the infrastructure (Infrastructure Criticality) that can recover metals from complex designed “mineral” mixtures. Base metals are at the heart of a Circular Economy, therefore key enablers of the Internet-of-Metallurgical-Things.
Keywords: Resource efficiency base metals, Recycling, System integration, Design for Recycling (DfR)
  • Invited lecture (Conferences)
    International Conference Recycling of Non-Ferrous Metals under the Patronage of President of KGHM Polska Miedz S. A. Herbert Wirth, 02.-04.03.2016, Krakow, Polen

Permalink: https://www.hzdr.de/publications/Publ-24584
Publ.-Id: 24584


Qualifizierung von CFD-Methoden für die Nukleare Sicherheitsforschung

Lucas, D.
The presentation gives an overview about the actual work in the department "Computationa Fluid Dynamics" of the Institute of Fluid Dynamics
Keywords: CFD, two phase flow, model development
  • Invited lecture (Conferences)
    Fachtagung der KTG-Fachgruppen, 17.-18.11.2016, KIT, Eggenstein-Leopoldshafen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24583
Publ.-Id: 24583


Model Developments to predict the Critical Heat Flux

Krepper, E.; Ding, W.
The presentation gives an overview on CFD-model delvelopments to predict the critical heat flux. Boiling is a very effective heat transfer mechanism but limited to the critical heat flux. The correct simulation of this phenomenon contributes to the safely and economical operation of energy generating facilities. Heat flux partition algorithms are presented. A more detailed description of the phenomena in the bulk is shown. Actual tendencies for the correct simulation of the microscopic phenomena by sublayer models are described.
Keywords: CFD, two phase flow, heat and mass transfer, boiling, critical heat flux
  • Invited lecture (Conferences)
    Fachtagung der KTG-Fachgruppen, 17.-18.11.2016, KIT, Eggenstein-Leopoldshafen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24582
Publ.-Id: 24582


Quantum Interference Controlled Current in InSb Injected by intense Terahertz Radiation

Bühler, J.; Schmidt, C.; Fischer, J.; Leitenstorfer, A.; Schneider, H.; Helm, M.; Pashkin, A.; Seletskiy, D. V.
Quantum interference between one- and two-photon absorption pathways is exploited for all-optical injection of charge current in InSb at 10 K. Polar-asymmetric excitation is synthesized by superposing intense output from a free electron laser centered at 31 THz with the phase-locked second harmonic. The relative phase between the two frequency components controls the directionality of the injected current. This demonstration motivates applications of intense synthetic pulses for resonant excitation, control and probing of various low-energy and correlated degrees of freedom.
Keywords: free-electron laser, optical current injection, coherent control

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Permalink: https://www.hzdr.de/publications/Publ-24581
Publ.-Id: 24581


Nonlinear Multi-Terahertz Excitation of Strongly Correlated Materials

Pashkin, A.
Invited talk at the Gordon Reserach Conference "Ultrafast Phenomena in Cooperative Systems"
Keywords: nonlinear THz spectroscopy, strongly correlated systems, high-field THz pulses
  • Invited lecture (Conferences)
    Gordon Research Conference "Ultrafast Phenomena in Cooperative Systems", 14.-19.02.2016, Lucca (Barga), Italy

Permalink: https://www.hzdr.de/publications/Publ-24580
Publ.-Id: 24580


FEL-based nonlinear THz spectroscopy at the ELBE accelerator

Pashkin, A.
Invited talk at the workshop on an accelerator based source for nonlinear THz science at SwissFEL. Organized by the Paul-Scherrer-Institut.
Keywords: free-electron laser, high-field THz spectroscopy
  • Invited lecture (Conferences)
    Workshop on an accelerator based source for nonlinear THz science @ SwissFEL, 03.-04.10.2016, Windisch, Switzerland

Permalink: https://www.hzdr.de/publications/Publ-24579
Publ.-Id: 24579


Recycling 4.0: Circular Economy Engineering & Metallurgy

Reuter, M. A.
CE: Circular Economy
Energy and materials: Product Centric Recycling–
Circular Economy within a Corporation

SIMP: System Integrated Metal Production
- Metallurgical infrastructure & knowledge of key importance
- Internet-of-Metallurgical-Things – Web of Metals

CEE: Circular Economy Engineering – Recycling 4.0
– Digitalized link of all stakeholders
– Quantification of resource efficiency
– Informing society in an understandable CE-paradigm
  • Invited lecture (Conferences)
    Sustainable metals recovery from electronic waste, 08.-10.02.2016, Perth, Australien

Permalink: https://www.hzdr.de/publications/Publ-24578
Publ.-Id: 24578


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