Suppression of stimulated Raman scattering at ultra relativistic laser power: Effect of localization

Abstract

The filamentation of the high-power laser beam is investigated by taking off axial contribution when relativistic nonlinearity is considered. The effect of filamentation of the laser beam is studied on the localization of the electron plasma wave (EPW) and on the stimulated Raman scattering (SRS). The semi-analytical solution of the nonlinearly coupled EPW equation in the presence of laser beam filaments has been found. It is observed that due to this nonlinear coupling between two waves, localization of EPW takes place. This localization of EPW affects the Eigen frequency and damping of plasma wave. The new enhanced damping of the plasma wave has been calculated and it is found that the SRS process gets suppressed due to the localization of plasma wave in laser beam filamentary structures. For typical laser beam and plasma parameters with wavelength λ (=1064 nm), power flux (=1018 W cm−2) and plasma density n/ncr (=0.2); the SRS back reflectivity is found to be suppressed by a factor of approximately 8%.