驱动激光束间相干性以及对背向散射影响的研究

早期的研究表明, 束匀滑技术能够有效地抑制高功率激光与等离子体相互作用中产生的各种参量不稳定性, 大大减少受激布里渊散射和受激拉曼散射. 但在NIF最近的实验研究中发现, 受激布里渊散射和受激拉曼散射份额远远高于预期, 原因可能与驱动激光束间的相干性有关. 本文利用"神光II"装置两路倍频纳秒激光辐照金平面靶, 研究了小口径取样情况下两者背向散射的能量和光谱在不同驱动激光相干条件下的变化情况. 初步结果表明, 激光束间存在着较强的相干性, 并且随着束间相干程度的增加, 背向散射也逐渐增强.

Research of coherence between driven-laser beams and its influence on backscatter

Previous studies have shown that the technology of beam smoothing may effectively control parameter instabilities within the laser-plasma interaction, and greatly reduce stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS). However, the recent experimental results on NIF revealed a much higher SBS and SRS than expected, one possible reason is due to the coherence between incident laser beams. In our research, two laser beams from "Shenguang II" facility are employed to irradiate an Au plate target, the energy and spectra of the backscattered light are measured in different coherent conditions. The results show that the driven-laser beams strongly interfere with each other, and usually the backscatter becomes strong gradually with the increase of coherent degree between the incident beams.