高强度二倍频激光辐照银薄膜靶的烧蚀和X光辐射实验研究

Experimental research on X-ray radiation and ablation of an Ag foil targets irradiated by high intensity 2ω_0 laser light beam

激光聚变物理实验中,背光透视照相是靶丸内爆动力学过程观测的重要方法.Ag是一种重要的背光材料,激光辐照产生的等离子体可以产生强L线辐射,研究其烧蚀和辐射特性,对提高内爆靶丸背光透视照相的图像质量具有十分重要的意义.在神光II装置上,采用第九路输出的2ns,～5×10(14)W/cm2,526.5nm激光均匀辐照Ag薄膜靶,实验研究了其烧蚀特性,获得了银薄膜靶在激光烧蚀驱动下的飞行轨迹和飞行速度的数据.实验结果与一维辐射流体力学模拟结果相符.火箭模型对实验数据进行拟合,得到了Ag材料的质量烧蚀速率和烧蚀压的数据.采用平面晶体谱仪和X射线二极管探测器阵列观测等离子体的辐射特性,获得了Ag等离子体辐射光谱和L线转换效率,实验结果对激光聚变内爆靶丸背光照相的实验设计具有重要的参考价值.

The characteristics of radiation and ablation are investigated for an Ag foil irradiated with 2 ns,～5×1014 W/cm2, 526.5 nm laser at SGII laser facility. The flight trajectory and velocity of the Ag foil are measured by X-ray streak camera. The experimental results show that they are in good agreement with simulations of one-dimensional radiation hydrodynamics code multi-1d using a flux-limited f=0.01. A rocket model is used to fit the experimental data, and the mass ablation rate and ablation pressure are obtained. The L-shell X-ray conversion and spectra of the laser-produced Ag plasma are measured with a Bragg crystal spectrometer and an array of X-ray diodes. The design for X-ray backlighting radiograph experiments will benefit from these experimental results. The result and method presented in this article are significant for the ablation research on the capsule shell and cavity wall material in laser fusion ignition experiment.