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针对超高压下透明材料的高压离化机理,分析了透明材料中冲击波直接诊断技术的基本方法.利用Drude-自由电子气模型,分析了不同冲击压力下冲击波阵面反射率的变化.从理论上比较了不同探针光波长反射率的区别,发现探针光波长为660nm时比探针光波长为532nm时获得的冲击波阵面反射率要高.对探测器“致盲”问题也进行了研究.通过分析反射信号的时间顺序和强度大小,发现“致盲”效应是由X光对透明窗口离化引起的.同时,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.通过实验结果,得到蓝宝石中冲击波速度为35km/s时,其波阵面的反射率约为40%.通过理论分析和实验数据比对的方法,验证了蓝宝石中的减速曲线.给出了加蓝宝石窗口后的测速公式.经过和实验对比,确认了测速公式的正确性.
Aiming at the high pressure ionization mechanism of transparent materials under ultra-high pressure, the basic method of direct shock wave diagnosis in transparent materials is analyzed. The change of the reflectivity of shock wave front under different impact pressures is analyzed by using Drude-free electron gas model. The difference of the wavelength reflectance of different probes was compared and it was found that the reflectance of the shock wave front obtained when the wavelength of the probe light is 660 nm is higher than that of the shock wave front obtained when the wavelength of the probe light is 532 nm. By analyzing the chronological order and strength of the reflected signals, we find that the “Blind” effect is caused by X-ray ionization of the transparent window.At the same time, it is found that the leading edge arrival time and the X-ray distance The time of arrival of shock wave signal is later than that of X-ray ionization.The experimental results show that when the shock wave velocity of sapphire is 35km / s, the reflectivity of the wavefront is about 40% .According to the theoretical analysis and The comparison of experimental data shows that the deceleration curve of sapphire is validated, and the formula of velocity after sapphire window is added.According to the experimental comparison, the correctness of velocity formula is confirmed.