Self-Absorption Of Synchrotron Radiation In A Laser-Irradiated Plasma

Electrons at the surface of a plasma that is irradiated by a laser with intensity in excess of1023Wcm- 2 are accelerated so strongly that they emit bursts of synchrotron radiation. Although the combination of high photon and electron density and electromagnetic field strength at the plasma surface makes particle-particle interactions possible, these interactions are usually neglected in simulations of the high-intensity regime. Here we demonstrate an implementation of two such processes: photon absorption and stimulated emission. We show that, for plasmas that are opaque to the laser light, photon absorption would cause complete depletion of the multi-keV region of the synchrotron photon spectrum, unless compensated by stimulated emission. Our results motivate further study of the density dependence of quantum electrodynamics phenomena in strong electromagnetic fields.