Ultrafast ion heating above 1 keV temperautres in solid density plasmas driven by ultrashort relativistic laser pulses


Ultrafast ion heating above 1 keV temperautres in solid density plasmas driven by ultrashort relativistic laser pulses

Huang, L. G.; Cowan, T.

Bulk ion heating driven by high power laser pulses is a fundamental scientific issue and of great interest to the potential applications such as nuclear excitation by electronic processes, inertial confinement fusion and so on. Yet, most theoretical and experimental investigation focus on several hundred picoseconds to nanosecond time scale evolution of ion heating dynamics, relying on radiation-hydrodynamic simulations and high energy laser facilities with the order of nanosecond pulse durations. Both the theoretical and experimental methodologies have constraints. In one hand, the hydrodynamic simulations may smooth out the kinetic effects in solid density plasmas such as species thermal decoupling, spatial mixing and separation. In the other hand, the experimental access using several hundred to kilo-Joule laser facilities is quite limited at present.

We present our recent results on ultrafast ion heating dynamics in solid buried layer targets driven by relativistic laser pulses with tens to hundreds of femtosecond pulse durations and high repetition rates[1]. The kinetic simulations using Particle-in-Cell methodology showing that the light ions within highly compressed solid density plasmas can be heated above 1 keV temperature in several hundred femtosecond time to picosecond time scales. We also found that significant instabilities and ion species mixture showing up which are originated from the interfaces of the solid buried layer targets. The possible heating mechanisms during the internal expansion and compression passage will be discussed and addressed.

In order to connect the ion heating dynamics seen in simulations with experiments, we will discuss the role of in-situ synthetic diagnostics that mimic experimental diagnostics. As one example, analyzing the energy spectrum and angular distribution of generated neutrons is possible to determine the ion temperature and distinguish the beam fusion and thermonuclear fusion, which is a conventional diagnostic method in experiments currently. The other key example we propose to directly probe the buried layer dynamics with coherent scattering techniques using hard X-Ray Free Electron Lasers, which is in principle and feasible to allow for probing fundamental plasma properties in nanosecond and femtosecond resolutions of plasma processes for the first time in the near future[2].

Reference:

[1] L. G. Huang et al., Phys. Plasmas 20, 093109 (2013)
[2] http://www.hibef.eu/

Keywords: Ion Heating; High power laser; XFEL; solid plasmas

  • Lecture (Conference)
    1st International Conference onMatter and Radiation at Extremes, 08.-12.05.2016, Chengdu, China

Permalink: https://www.hzdr.de/publications/Publ-23723
Publ.-Id: 23723