Helmholtz Young Investigator Group – Katerina Falk
Ultrafast X-ray Methods for Laboratory Astrophysics
Project title: Development of novel laser wakefield probes for the study of structure and transport properties of astrophysically relevant dense plasmas
The primary research focus of this group is the study of transport properties and structure of plasmas with densities ranging from relatively low (dilute gas) to solid ones and moderate temperatures (0.1-100 eV) with a special relevance to Astrophysics. This includes the Warm Dense Matter (WDM) region. Such plasmas are often partially ionized and are subject to strong particle coupling effects and high electron quantum degeneracy. These strongly coupled plasmas are common in many astrophysical objects such as interiors of stars and planets or astrophysical shocks (supernova explosions, collisions, astrophysical jets, etc.) and it is readily created as a transient state between solids and low-density plasmas during laser-matter interactions including the implosion of deuterium-tritium fuel pellets in Inertial Confinement Fusion (ICF). The equation of state, electric conductivity, particle stopping power, diffusion as well as mixing of plasmas, transport of heat and radiation in dense plasmas are responsible for the layer structure and convection in planets and stars, their formation or the dynamics of the dynamos inside their cores, as well as structure in astrophysical shocks, supernovae or accretion disks, and successful implementation of several approaches to the ICF approach to ‘clean’ energy production.
Due to the complicated nature of these plasma states owing to strong quantum and correlation effects, the theoretical description of the thermodynamic properties remains very limited. Under the studied conditions many standard models break down, the particle stopping powers and energy deposition in dense plasmas are largely unknown and very difficult to model, the classical hydrodynamic description of shock propagation becomes invalid during nonlocal electron transport across the shockfront and the equation of state that defines the thermodynamic state and microscopic structure of these plasmas is highly inaccurate. Thus, accurate experimental measurement is required to verify the theoretical models used to describe these phenomena. For the study of transport properties, precise experimental methods to both create such plasma in a desired and controllable state as well as its characterization with precise diagnostic methods must be developed.
The key parameter is the ultrafast measurement (with resolution of tens of femtoseconds) capable of resolving the non-equilibrium dynamics responsible for transport properties in these systems. We are developing a novel experimental platforms combining long (ns) and short pulse (fs and ps) lasers. In these experiments we utilize the standard plasma diagnostics with novel methods under development including new spatially resolved x-ray techniques based on Laser-Wakefield Acceleration (LWFA) and K-alpha sources from microstructured targets driven by femtosecond lasers. Tunable external magnetic fields are used to provide controlled conditions under which a precise comparison with theoretical models is possible. The experimental findings are used to benchmark the development of theoretical and computational models leading to answer important questions in astrophysics as well as develop new technologies.
Our experiments are primarily carried out at the DRACO laser facility at HZDR, where we use the novel laser-driven betatron (LWFA) as an ultrafast x-ray source (30 fs pulse duration) for x-ray absorption spectroscopy with angularly resolving spectrometers. We also carry out experiments at other high power laser systems worldwide (OMEGA, LULI, PALS, PHELIX, European X-FEL and HIBEF, etc.). For the generation of the plasma samples we use both shocks driven directly by lasers as well as isochoric heating with x-rays and protons that generate more homogeneous samples of larger size. An integral part of our work is the development of novel methods and instruments with a particular focus on x-ray spectroscopy.
|Xiayun Pan||PhD student|
|Pablo Pérez Martín||PhD student|
|Lenka Hronová||Bc student (Czech Technical University)|
MSc / BSc positions available!
Summer research projects for undergraduate students are also available through the HZDR Summer Student Program.
Contact Katerina Falk for further information.
Teaching and outreach
- Winter semester 2018/19:
Understanding the Universe (Proseminar)
- ATHENS course at the Czech Technical university 2016 and 2017:
Lecture on Warm Dense Matter
- PyCon CZ 2017 Prague, June 9, 2017:
Lecture: Science with the world’s biggest lasers
- TEDx Zlín, Nov 16, 2015
- K. Falk
Experimental Methods for Warm Dense Matter Research
High Power Laser Science and Engineering 6, 59 (2018)
- K. Falk, M. Holec, C. J. Fontes, C. L. Fryer, C. W. Greeff, H. M. Johns, D. S. Montgomery, D. W. Schmidt, and M. Šmíd
Measurement of Preheat Due to Nonlocal Electron Transport in Warm Dense Matter
Physical Review Letters 120, 025002 (2018)
- M. Šmíd, I. Gallardo González, H. Ekerfelt, J. Björklund Svensson, M. Hansson, J. C. Wood, A. Persson, S. P. D. Mangles, O. Lundh, and K. Falk
Highly efficient angularly resolving x-ray spectrometer optimized for absorption measurements with collimated sources
Review of Scientific Instruments 88, 063102 (2017)
- U. Zastrau, E. J. Gamboa, D. Kraus, J. F. Benage, R. P. Drake, P. Efthimion, K. Falk, R. W. Falcone, L. B. Fletcher, E. Galtier, M. Gauthier, E. Granados, J. B. Hastings, P. Heimann, K. Hill, P. A. Keiter, J. Lu, M. J. MacDonald, D. S. Montgomery, B. Nagler, N. Pablant, A. Schropp, B. Tobias, D. O. Gericke, S. H. Glenzer, and H. J. Lee
Tracking the density evolution in counter-propagating shock waves using imaging X- ray scattering
Applied Physics Letters 109, 031108 (2016)
- K. Falk, E. J. Gamboa, G. Kagan, D. S. Montgomery, B. Srinivasan, and J. F. Benage
Equation of State Measurements of Warm Dense Carbon Using Laser-Driven Shock and Release Technique
Physics Review Letters 112, 155003 (2014)
- K. Falk, C. A. McCoy, C. L. Fryer, C. W. Greeff, A. L. Hungerford, D. S. Montgomery, D. W. Schmidt, D. G. Sheppard, J. R. Williams, T. R. Boehly, and J. F. Benage
Temperature measurements of shocked silica aerogel foam
Physical Review E 90, 033107 (2014)
- M. Roth, D. Jung, K. Falk, N. Guler, O. Deppert, M. Devlin, A. Favalli, J. Fernandez, D. Gautier, M. Geissel, R. Haight, C. E. Hamilton, B. M. Hegelich, R. P. Johnson, F. Merrill, G. Schaumann, K. Schoenberg, M. Schollmeier, T. Shimada, T. Taddeucci, J. L. Tybo, F. Wagner, S. A. Wender, C. H. Wilde, and G. A. Wurden
Bright Laser-Driven Neutron Source Based on the Relativistic Transparency of Solids
Physical Review Letters 110, 044802 (2013)
- K. Falk, S. P. Regan, J. Vorberger, B. J. B. Crowley, S. H. Glenzer,6S. X. Hu, C. D. Murphy, P. B. Radha, A. P. Jephcoat, J. S. Wark, D. O. Gericke, and G. Gregori
Comparison between x-ray scattering and velocity-interferometry measurements from shocked liquid deuterium
Physical Review E 87, 043112 (2013)
- S. P. Regan, K. Falk, G. Gregori, P. B. Radha, S. X. Hu, T. R. Boehly, B. J. B. Crowley, S. H. Glenzer, O. L. Landen, D. O. Gericke, T. Döppner, D. D. Meyerhofer, C. D. Murphy, T. C. Sangster, and J. Vorberger
Inelastic X-Ray Scattering from Shocked Liquid Deuterium
Physical Review Letters 109, 265003 (2012)