超短超强激光与稀薄等离子体相互作用背向受激Raman谱特性模拟

Simulation of stimulated Raman backscatter from interaction between ultrashort,ultrahigh intensity laser and tenuous plasma

利用LPIC++程序模拟了超短超强脉冲与稀薄等离子体相互作用产生的背向受激Raman谱。结果证明:在极端相对论条件下,背向受激Raman谱不再是通常所指的弱耦合模式,而进入强耦合模式。频谱加宽,并融合在一起;各谱峰之间的频移不再以等离子体波的频率为间隔,而是小于电子等离子体波的频率。模拟了各种条件下的背向散射Raman谱特性,结果显示:随着密度的提高,背向受激Raman谱的强度也将提高,这与理论结果符合得较好。

This paper studies the excitation of the stimulated Raman backscatter of ultrashort and ultrahigh intensity laser pulse. Through one dimentional particle-in-cell code LPIC＋＋, it is found that in the relativitic condition, the stimulated Raman backscatter is not in the mormal mode but strongly coupled. The frequency spectra become broad with blueshift and the interval between the peaks are greater than the frequency of the plasma wave frequency. These results are consistent with the prediction of a srongly coupled Raman theory.