Strong kinetic effects in cavity-induced low-level saturation of stimulated Brillouin backscattering for high-intensity laser-plasma interaction

Abstract

A kinetic mechanism for the saturation of Brillouin backscattering in the high-intensity regime is presented. The reflectivity goes through several characteristic phases and terminates in a low-level quasistationary state of a few percent. This low-level saturation is due to the creation of cavities in the plasma. The process responsible for cavity formation is linked to Coulomb explosions in the bulk plasma. Along with the cavity formation, particles are accelerated up to energies of $100\mathrm{keV}$ . Strong electron and ion heating and acceleration are the characteristics of this saturation mechanism for stimulated Brillouin backscattering. The cavities are filled with electrostatic and electromagnetic fields. Whereas the electrostatic ones are quickly dissipated, the electromagnetic ones are stable and have intensities up to 30 times the incident laser intensity.