磁驱动准等熵加载下Z切石英晶体的折射率

基于CQ4脉冲功率实验装置开展了Z-切石英晶体在磁驱动准等熵加载下的窗口折射率修正关系研究. 实验中采用激光波长1550 nm的双源光外差测速仪测量获得了LiF窗口和Z-切石英晶体窗口与不同厚度极板界面的粒子速度. 利用反积分方法由实验测得的LiF窗口与极板界面粒子速度计算得到了极板的加载磁压力历史; 以获得的磁压力为输入条件, 采用LS-DYNA计算软件正向计算得到石英晶体窗口与极板界面的真实粒子速度历史. 由实验获得的Z-切石英晶体窗口/极板界面表观粒子速度和计算得到的真实粒子速度, 获得了Z-切石英晶体弹性极限内的连续的折射率修正关系, 将其折射率修正关系的适用压力范围拓宽至14.55 GPa. 表观粒子速度与真实粒子速度关系采用线性拟合时, 折射率修正关系为n=1.087 (± 0.008)+0.4408ρ/ρ₀, 与冲击数据拟合的结果一致. 由折射率实验数据对Z-切石英晶体的极化率分析认为, 在其弹性极限压力范围内加载路径和温度对折射率的影响可以忽略.

Refractive index of Z-cut quartz under magnetically driven quasi-isentropic compression

The refractive index of Z-cut quartz under magnetically driven quasi-isentropic compression is researched by using the pulsed power generator CQ-4. Its velocities of interface between the aluminum panel and the window are measured by a four-channel dual laser heterodyne velocimeter, which is operated at an incident laser wavelength of 1550 nm. The history profile of magnetic pressure on the electrodes is obtained by a backward integration calculation of the aluminum/LiF interface velocity. And then the pressure history profile is used in the LS-DYNA simulation to get the true particle velocity of the aluminum/quartz interface. Combining with the apparent particle of aluminum/quartz interface which is obtained from experiments, a continuous index of refraction in Z-cut quartz has been obtained at up to a pressure of 14.55 GPa as the longitudinal stress is gradually increased to its elastic limit. The relation between the apparent particle and true particle velocities can be fitted by a polynomial, and the required derivative obtained by differentiation of that polynomial. Refractive index determined from the linear fitting parameters is n=1.087 (± 0.008)+0.4408 ρ/ρ₀, which agrees well with the previous shock results. Results from polarizability analysis suggest that the temperature and loading path should have less effect on the refractive index of Z-cut quartz within its elastic limit.