预热效应影响下冲击波速度推算方法

Shock Wave Velocity Calculation Under X-Ray Preheat Effect

介绍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。利用成像型速度干涉仪技术研究了间接驱动实验中产生的预热效应对冲击波速度计算的影响。对预热效应出现的时间点进行了分析,发现在辐射温度高于160 eV以后,不能从现有速度干涉仪系统获得的实验结果直接反演出冲击波速度。对实验数据进行了处理,获得了预热出现时间点的实验数据,发现预热效应出现在方波激光脉冲平台期到达时刻,在激光最强处达到最大,而且在激光脉冲平台期结束后,预热效应可以逐渐恢复。实验发现,对辐射温度高于160 eV获得的实验结果,可以从条纹断点直接外推,得到冲击波减速数据。讨论了条纹外推方法处理间接驱动条件下方波打靶时,使用固体无机透明材料作为窗口获得的实验结果。

The technique of measuring the shock wave velocity directly in the transparent material under the ultra-high pressure is introduced.The preheat effect on shock wave velecity calculation in the indirect driven experiment is studied with imaging velocity interferometer system for any reflector（IVISAR）.After analyzing the beginning time of preheat effect,it is found that the shock wave velocity cannot be deduced directly from the experimental data when the radiation temperature is higher than 160 eV with IVISAR.From the experimental data,the starting point of preheat effect is consistent with the laser pulse,and it is found that the preheat effect is the worst when the intensity of laser pulse is the highest.The preheat effect recovers after the intensity of laser pulse decreases.For the experimental data above 160 eV,the shock velocity curve can be calculated by extrapolating the background stripe to the jumping edge.This method is suitable for processing experimental data gotten from the indirectly driven square wave laser and the inorganic transparent window.