超短超强激光与气体靶相互作用中的背向受激Raman散射

Diagnostic research of stimulated Raman back scattering in ultrashort-ultraintense laser interaction with gas target

实验诊断测量了超短超强激光与气体靶相互作用产生的背向受激Raman散射,在实验条件下呈现强耦合模式,背向受激Raman散射出现非线性Stokes多峰伴线结构,峰值的频率间隔小于等离子体波的频率,可以大致地推断出激光打靶过程中产生的等离子体密度偏低,其结果与等离子体强耦合理论计算结果一致。

The stimulated backward Raman scattering generated by femosecond laser interaction with gas target was measured. In the condition of experiment, the stimulated Raman baekscatter（SRS） is in the strongly coupled mode, and several nonlinear Stokes satellite peaks appeare in the scattering spectrum. The frequency space of Stokes peaks is smaller than the plasma wave frequency. The plasma density range of laser interaction with gas target deduced from backward SRS is 5 × 10^18 cm^-3. These results are consistent with the prediction of a strongly coupled Raman theory.