Stimulated Raman side and backscatter instabilities of crossed laser beams in plasma

Stimulated Raman scattering (SRS) instability due to two nonlinearly coupled laser beams propagating in homogeneous, thermal plasma is analyzed. The temporal evolution equations for pump, scattered and Langmuir waves excited due to the interaction are set up. Using numerical techniques temporal evolution of amplitudes of pump, scattered and resultant Langmuir waves for side and back SRS instabilities have been obtained in the nonrelativistic regime. The temporal growth rate, saturation time and saturation amplitude of waves excited by two crossed (perpendicular) lasers are studied and compared with the single beam case. The model considers pump depletion to be the dominant saturation mechanism. The study points towards a new concept for generation of high amplitude Langmuir waves.

Automated summary

This study analyzes the stimulated Raman scattering (SRS) instability caused by two non-linearly coupled laser beams propagating in homogeneous, thermal plasma. The temporal evolution equations for the pump, scattered, and Langmuir waves are established to describe their interactions. Numerical techniques are used to obtain the temporal evolution of the amplitudes of the pump, scattered, and resultant Langmuir waves for side and back SRS instabilities in the nonrelativistic regime. The study examines the temporal growth rate, saturation time, and saturation amplitude of waves excited by two crossed lasers and compares them with the single beam case. The model considers pump depletion as the dominant saturation mechanism. The findings suggest a new concept for generating high amplitude Langmuir waves.