Stimulated Brillouin Scattering of Gaussian Laser Beam in Relativistic Plasma

Abstract

This paper presents an investigation of stimulated Brillouin scattering (SBS) of Gaussian laser beam in relativistic plasma. The pump beam interacts with a pre-excited ion-acoustic wave thereby generating a back-scattered wave. In the high intensity laser beam, electron oscillatory velocity becomes comparable to the velocity of light, which modifies the refractive index of plasma due to increase in the electron mass. This modification of refractive index affects the incident laser beam, ion-acoustic wave and back scattered beam. We have set up non-linear differential equations for the beam width parameters of the main beam, ion-acoustic wave, back-scattered wave and derived expression of SBS-reflectivity by taking full non-linear part of the dielectric constant of relativistic plasma with the help of moment theory approach. It is observed from the analysis that focusing of waves greatly affects the SBS reflectivity.