Speaker
Jiri Vyskocil
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.2031.pdf
Simulations of bremsstrahlung emission in interactions of ultra-intense
laser pulse with foil target
Jiří Vyskočil1,2 , Ondřej Klimo1,2 and Stefan Weber2
1 Czech Technical University in Prague, Prague, Czech Republic 2 Institute of Physics AS CR,
Dolní Břežany, Czech Republic
Contemporary and upcoming multi-petawatt lasers will produce short pulses which, when
focused to a spot on the order of a few microns, generate strong electromagnetic fields of inten-
sities I ∼ 1 × 1022 W/cm2 , opening new possibilities in generating laboratory γ rays by a variety
of processes involving fast electrons which are generated during the interaction of an intense
laser pulse with a target. Two main sources of energetic photons generated in an interaction
with a thin foil target are bremsstrahlung and radiation reaction (including non-linear Compton
scattering).
Bremsstrahlung emission from the interaction of a short ultra-intense laser pulse with solid
foils is investigated using Particle-in-Cell (PIC) code EPOCH. A module for simulating bremsstrahlung
has been implemented in the PIC loop to self-consistently account for the dynamics of the laser-
plasma interaction, plasma expansion, and the emission of γ ray photons. The conversion effi-
ciency of the energy of the laser pulse to the energy of the γ rays is studies as a function of the
intensity of the driving pulse, the thickness of the target, the pre-plasma profile, and the target
material. In thin targets, refluxing of hot electrons plays an important role. Simulations reveal
that the angular distribution of the emitted photons exhibits a four-directional structure with
the angle of emission decreasing with the increase of width of the target. It is shown that the
dependence of the mean angle of emitted photons on target thickness is due to the hot electrons
losing energy in the TNSA field during refluxing.
