整形脉冲驱动下透明材料离化现象

Ionization of transparent material driven by shock timing technique

利用成像型速度干涉仪研究了大型激光原型装置整形脉冲驱动实验中产生的预热效应。对冲击波传输过程进行了分析,发现第1和第2个冲击波的起始时刻都在胶层里面,第3个冲击波的起始时刻在熔石英窗口里面。实验发现,由于X光离化效应的影响,第1和第2个冲击波传输引起的条纹跳变并没有观察到。第2和第3个激光脉冲前半部分产生的离化效应将透明窗口完全漂白,导致成像型速度干涉仪获得的条纹图出现了间断。实验观察到了第3个激光脉冲驱动的冲击波在熔石英中产生的加速和减速过程。对整形脉冲获得的实验结果进行了初步解释,得出现有条件下整形脉冲驱动应注意的问题为:控制最高辐射温度,选用带隙大的窗口材料,尽量减小胶层的厚度。

The preheating effect on planer-window materials in direct driven experiments was studied with imaging velocity interferometer system for any reflector（VISAR）. The transmitting process of shock wave in the transparent material has been analyzed. It is found that the first and second shocks transform in adhesive, and the third shock transforms in fused silica. From the experiment data, no disconnected stripe induced by the first and second shocks is observed due to the ionization caused by X-ray radiation. Because the transparent adhesive is bleached by the second laser pulse and the first half of the third, the recorded stripe is disconnected. The acceleration and deceleration processes of shock wave in fused silica has been observed. After we explained the shock-timing data, some conclusions can be drawn for shock timing technique, which are that the maximum radiation temperature should be control below the bleaching temperature, the band gap of transparent material should be large and the thickness of adhesive should be as thin as possible.