2ns,351nm激光黑腔靶受激Raman散射实验研究

Stimulated Raman scattering from interaction of 2ns,351nm laser with hohlraum

介绍了在神光Ⅱ装置上开展的长脉冲2 ns,351 nm激光与黑腔靶相互作用的实验,报道了受激Raman散射光时间分辨谱图及能量测量的实验结果。长脉冲2 ns激光注入小腔靶(700μm×1 250μm)时,激光辐照缝靶产生的SRS光能量是激光与全腔靶作用产生的SRS光能量的1.3倍。在2 ns激光与不同尺寸黑腔靶作用的情况下,激光辐照小腔靶产生的SRS光能量比标准腔靶(800μm×1 350μm)产生的SRS光能量高1.6倍。由于激光功率密度下降,2 ns激光打靶SRS散射光要弱于短脉冲1 ns激光打靶,但持续时间稍长。实验结果表明:长脉冲2 ns激光与标准腔靶相互作用时,等离子体“堵腔效应”比较严重,标准腔靶尺寸不再合适。

An experiment of laser-plasma interaction in hohlraum plasmas produced by laser beams with 351 nm wavelength, 2 ns pulse duration at SGII laser facility was reported in this paper. The time-resolved spectra and energy of scattered light by stimulated Raman scattering （SRS） were measured. When 2 ns laser entered into a small hohlraum（Ф700μm×1250μm）, the energy of scattered light＇from a slot hohlraum was 1.3 times that from a hohlraum. With different hohlraum size, the energy of scattered light from a small hohlraum was 1.6 times higher than that from a standard hohlraum（Ф800μm×1350μm）. Compared with Ins laser, when 2 ns laser interacted with hohlraum, the energy of SRS light was lower because of the decline of laser power, while the duration time was longer. The experimental results show that ＂hohlraum closure＂ is serious and that the size of standard hohlraum is unsuitable for the interaction of 2 ns laser light with the hohlraum.