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10Complex Systems of Charged Particles and their Interactions with Electromagnetic Radiation 2018
INTERACTION OF RELATIVISTICALLY INTENSE LASER PULSES WITH SOLID
AND LOW-DENSITY TARGETS
N.E. Andreev1,2
1 Joint Institute for High Temperatures of the Russian Academy of Sciences, Moscow 125412, Russia 2Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia
Various mechanisms of heating and generation of hot electrons under the action of relativistically intense laser pulses on solid and low-density targets are considered. Experimental data obtained at the facilities of PHELIX (Darmstadt) and JETI40 (Jena) are discussed.
New simulation results on relativistic laser interaction with near critical density CHO foams demonstrate strong improvement of the electron laser based sources toward higher energy and higher charge carried by electron beam. In particular, interaction of the relativistic laser pulse with near critical plasma layer leads to effective generation of highly energetic electrons of tens of MeV energies caring the charge that many orders of magnitude exceed the value predicted by the ponderomotive Wilks scaling.
Results of the pilot hydro-dynamic simulations that are based on a wide-range two-temperature EOS, wide-range description of all transport and optical properties, ionization, electron and radiative heating, plasma expansion, and Maxwell equations (with a wide-range permittivity) for description of the laser absorption in solid targets are in excellent agreement with experimental results. According to these simulations, the generation of keV-hot bulk electrons is caused by the collisional mechanism of the laser pulse absorption in plasmas with a near solid step-like electron density profile. The laser energy firstly deposited into the nm-thin skin-layer is then transported into the target depth by the electron heat conductivity. This scenario is opposite to the volumetric character of the energy deposition produced by supra-thermal electrons.
