Effect of electron heating on self-induced transparency in relativistic intensity laser-plasma interaction

摘要

The effective increase of the critical density associated with theinteraction of relativistically intense laser pulses with overcritical plasmas,known as self-induced transparency, is revisited for the case of circularpolarization. A comparison of particle-in-cell simulations to the predictionsof a relativistic cold-fluid model for the transparency threshold demonstratesthat kinetic effects, such as electron heating, can lead to a substantialincrease of the effective critical density compared to cold-fluid theory. Theseresults are interpreted by a study of separatrices in the single-electron phasespace corresponding to dynamics in the stationary fields predicted by thecold-fluid model. It is shown that perturbations due to electron heatingexceeding a certain finite threshold can force electrons to escape into thevacuum, leading to laser pulse propagation. The modification of thetransparency threshold is linked to the temporal pulse profile, through itseffect on electron heating.