透明材料中冲击波速度直接测量技术

Measurement Technology of Shock Wave Velocity in the Transparent Material

本文提出了超高压条件下应用于透明材料中冲击波速度直接测量的成像型速度干涉仪技术。介绍了成像型速度干涉仪技术的光路结构和基本原理,给出全系统的光路图。分析了预热效应产生和冲击波到达时刻的时间顺序,发现方波驱动脉冲平台的前沿到达时刻和X光离化效应出现的时刻相同,冲击波信号到达时刻晚于X光离化时刻。验证了冲击波到达窗口材料时形成反射面的反射率会突然增高,可以通过该现象确认冲击波到达的时刻。给出了实验结果,分析了条纹间断是由于X光预热效应引起的,并且发现预热效应在激光脉冲平台期前沿进入靶腔后开始,平台期后沿结束后约400ps减弱到不影响冲击波信号探测。通过理论分析和实验数据比对的方法,确认了蓝宝石当中的减速曲线。给出了加蓝宝石窗口后的测速公式。经过实验对比,确认了测速公式的正确性。

The technique to measure directly the shock wave velocity in the transparent material for the ultra-high pressure is introduced. The optical lane and the basic rule for this technique is provided, and the time sequence of preheat effect and shock wave is analyzed. From the experiment data, it is found that the beginning point of preheat effect caused by X-ray is consistent with the laser pulse, and the preheat effect is the worst when the intensity of laser pulse is highest. The shock wave is later than the preheat effect. The reflection signal increases when the shock wave reaches the planar-window material. This increasing for reflection signal can be regarded as the beginning point of shock wave. The experiment data shows that the stripe loss is caused by the preheat effect. The preheat effect appear as soon as the flat of laser pulse transfers into the target cavity, and it decrease too low to disturb the detecting of shock wave after 400ps at the end of flat of laser pulse. The decreasing curve in the sapphire is confirmed by the comparison of experiment data and theoretical analysis. The formula to calculate the shock wave velocity is provided, and it is conformed by the experiment data.