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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.
Early studies have shown that beam smoothing can effectively suppress the various parameters instability caused by the interaction between high power laser and plasma and greatly reduce stimulated Brillouin scattering and stimulated Raman scattering.But in the recent NIF Experimental study found that stimulated Brillouin scattering and stimulated Raman scattering share far higher than expected, the reason may be related to the coherence between the driving laser beam.In this paper, “Shenuang Ⅱ ” device two times The frequency of nanosecond laser irradiation on the gold plane targets was used to study the changes of the backscattering energy and the spectrum of the small-aperture sampling under different driving laser coherence conditions.The preliminary results show that the laser beams have strong coherence And with the increase of coherence between beams, backscattering also gradually increases.