Four wave sidescattering absolute instability of stimulated Brillouin backscattering in plasmas

Abstract

A novel effect of sidescattering absolute instability due to stimulated Brillouin backscattering (SBBS) has been theoretically predicted. The effect is based on four wave mixing of the driver pump, a background propagating Stokes wave and two newly excited counterpropagating sidescattered Stokes waves. It is shown that the instability of the sidescattered Stokes components is absolute. The threshold value for this instability in the model of a homogeneous plasma slab is evaluated. The effect has ultimate importance for the explanation of the driver pump field intensity dependence in SBBS encountered in laser-plasma interaction experiments.