啁啾激光脉冲受激拉曼散射理论和粒子模拟

Theoretical and Numerical Studies on Stimulated Raman Scattering by a Chirped Laser Pulse

从入射光波、散射光波和等离子体波的三波耦合方程出发,推导小带宽频率啁啾对拉曼散射的影响.得到频率啁啾对拉曼背向散射有抑制作用,且背向散射不依赖于啁啾符号;正(负)啁啾对拉曼前向散射有微弱的增强(减弱)的作用.最后采用1D3V粒子模拟程序观测了不同啁啾参数下的受激拉曼散射现象,得到与理论分析一致的结果.

We analyze effect of a small-bandwidth linear frequency chirp on growth of Raman instability with coupled relativistic Maxwell-fluid equations.It is shown that threshold of Raman backward scattering is increased by frequency chirp with no dependence on the sign of chirp.And growth rate of Raman forward scattering increases（decreases） for a positive（negative） chirp.In addition 1D3V particle-in-cell simulations are performed.It shows agreement with theoretical analysis.