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.

中文翻译：

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用于研究等离子体中高功率激光器的相对论受激拉曼背散射的高阶微扰方法

研究了等离子体中高功率线性偏振激光脉冲的相对论受激拉曼背散射 (SRBS)。推导出存在相对论和质动力非线性联合效应的拉曼不稳定性非线性耦合方程。利用相对论流体-麦克斯韦模型中的高阶微扰方法，得到了一组非线性耦合方程，描述了两个散射电磁波和一个修正等离子体波的演化。然后使用耦合方程组的数值解研究 SRBS 过程的时间演变。结果表明，使用线性近似不能准确地采用相对论质量校正，并导致对扰动电流密度和拉曼散射的高估。我们的分析表明，