Current-filamentation instability in intense laser-solid interactions

The streaming of energetic charged particles can magnetize astrophysical and laboratory plasmas via the current filamentation instability. Over the last decades, there has been significant interest in the study of the current filamentation instability in intense laser-solid interactions, where it impacts fast electron transport and magnetic field amplification. We have used kinetic theory and simulations to study the interplay between electromagnetic, electrostatic and collisional effects in the development and nonlinear evolution of the instability in these environments. We show that in the case of strong asymmetry between fast and return current electrons, space-charge effects and ion motion become critical and lead to a very significant slow down of the instability. Collisional effects further constrain the spatial scales of the instability. These results are compared with recent experiments at LCLS, where the instability dynamics was directly resolved.