A new saturation mechanism, beam plasma instability with trapped electrons resulting in saturation of stimulated Raman backscattering (SRBS), is presented. The beam plasma instability can be excited due to interaction between beam electrons and background electrons and it will produce a new mode. Here, the trapped electrons can be considered as beam electrons with velocity vp(phase velocity of the plasma wave) and density nt (density of the trapped electrons normalized by nc, nc is the critical density for the incident laser light). This new mode will induce a sinusoidal density modulation and then this modulation will produce harmonic wave with modulation wave-number period δk to enhance this new mode. As reported previously, the density modulation can increase Landau damping of the plasma wave and decrease the resonant region where SRBS occurs. Therefore, SRBS will saturate due to beam plasma instability induced by the trapped electrons.

中文翻译：

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由于俘获电子引起的束等离子体不稳定性导致受激拉曼背散射饱和

提出了一种新的饱和机制，束等离子体不稳定性与捕获电子导致受激拉曼背散射 (SRBS) 饱和。由于束电子和背景电子之间的相互作用，束等离子体不稳定性会被激发，并且会产生一种新的模式。在这里，被困电子可以被认为是具有速度 vp（等离子体波的相速度）和密度 nt（被 nc 归一化的被困电子的密度，nc 是入射激光的临界密度）的束电子。这种新模式将引起正弦密度调制，然后该调制将产生调制波数周期为 δk 的谐波，以增强这种新模式。如前所述，密度调制可以增加等离子体波的朗道阻尼并减少发生 SRBS 的共振区域。