Relativistic and ponderomotive effects on stimulated Raman scattering of intense laser radiation in plasma

The effects of relativistic nonlinearities on stimulated Raman scattering (SRS) of mildly relativistic laser radiation propagating through preionized underdense plasma is studied. The nonlinear mode coupling equations and linearized growth rates of Raman instabilities in presence of combined effects of relativistic and ponderomotive nonlinearities are derived. The temporal evolution of SRS process is then studied and analyzed using numerical techniques in presence of the two nonlinearities. It is observed that relativistic effects now taken into account significantly affect the growth rates and the nonlinear evolution of SRS process as compared to the case where they are neglected. The study shows that inclusion of relativistic nonlinearities along with the ponderomotive nonlinearities destabilizes SRS process.