论文部分内容阅读
长脉冲激光打靶的直接驱动方式效率较高,但对激光强度变化非常敏感。利用测量自由面速度历史的方法对激光直接驱动准等熵压缩实验技术进行了分析,为改进激光直接驱动的准等熵压缩实验技术提供技术基础。介绍了国内在神光III原型装置上首次开展的激光直接驱动自由面准等熵压缩实验。对实验靶型、激光波形、典型实验结果以及实验中的关键技术进行了分析。在激光能量为1000 J的实验中,使用成像型速度干涉仪获得了较为理想的准等熵压缩条纹图。实验发现,自由面速度达到11.3 km/s时,自由面反射的探针光信号消失。通过对比Multi-1D软件的理论模拟数据与实验处理的结果,发现由于Al自由面缺少约束,这类实验会造成波系复杂化的问题,但是对主冲击的研究还是有意义的。对某些特殊材料,在很难找到阻抗匹配窗口的条件下,利用激光直接驱动方式研究材料高压响应特性提供了另一条可实施的技术途径。
The direct drive method for long pulse laser shooting is more efficient, but it is very sensitive to changes in laser intensity. The method of quasi-isentropic compression for laser direct driving was analyzed by means of measuring the history of free surface velocities, which provided the technical basis for improving the quasi-isentropic compression experimental technique of laser direct driving. This paper introduces the quasi - isentropic compression experiment of laser direct driving free surface firstly carried out in Shen Guang III prototype device in our country. The experimental targets, laser waveforms, typical experimental results and the key technologies in the experiment were analyzed. In the experiment of laser energy of 1000 J, an ideal quasi-isentropic compression fringe pattern was obtained by using imaging speed interferometer. Experiments show that when the free surface velocity reaches 11.3 km / s, the free-surface reflected probe optical signal disappears. By comparing the theoretical simulation data of Multi-1D software with experimental results, we find that due to the lack of constraints on Al free surface, such experiments will cause the wave system to be complicated, but the research on main shock is still meaningful. For some special materials, laser direct driving method is used to study the high pressure response of materials under the conditions that it is hard to find the impedance matching window, which provides another feasible technical approach.