LAUSR

The relativistic stimulated Raman back scattering (SRBS) of a high power linearly polarized laser pulse in the plasma is investigated. The nonlinear coupled equations of Raman instabilities in the presence of combined effects of relativistic and ponderomotive nonlinearities are derived. Using high-order perturbation method in relativistic fluid-Maxwell model, a set of coupled non-linear equations is obtained which describes the evolutions of two scattered electromagnetic waves and a modified plasma wave. The temporal evolution of SRBS process is then studied using numerical solutions of the set of coupled equations. The results showed that by using the linear approximation, the relativistic mass correction cannot be employed accurately and it leads to over-estimation of the perturbed current density and Raman Scattering. Our analysis shows that, in the relativistic regime, it is crucial to employ higher order perturbation method to obtain reliable results.