Transparency/Opacity of a Solid Target Illuminated by an Ultrahigh-Intensity Laser Pulse

Abstract

By means of one-dimensional particle-in-cell simulations of an ultraintense electromagnetic wave normally incident on an overdense plasma, the transition from a regime of wave reflection to one of penetration is observed, when laser irradiance is increased. Both cases display Doppler-redshifted backscattered light originating from a moving surface. The irradiance threshold for the transition is given as a function of electron density. The energy reflected and the kinetic energies in both electrons and ions are provided.