表面绝缘混合平面丝阵Z箍缩激光阴影图像诊断∗

摘要

基于脉冲半高全宽约为9 ns、波长为532 nm的Nd：YAG激光器,采用条纹相机和商用数码相机两种记录设备,建立了时间分辨和时间积分两种模式的激光阴影图像诊断系统,在“强光一号”装置上对表面绝缘混合平面丝阵Z箍缩等离子体开展了实验研究.实验结果表明：在融蚀过程中表面绝缘金属丝冕等离子体发展较普通金属丝慢,在t=44 ns 到t=56 ns之间,其平均膨胀速度分别为1.1×104 m·s−1和1.7×104 m·s−1；在等离子体滞止前10 ns的快速聚爆过程中,表面绝缘金属丝和普通金属丝两侧的平均聚爆速度分别为5.5×105 m·s−1和9.3×105 m·s−1,表面绝缘一侧等离子体滞止时间小于普通金属丝一侧,分别为5.9 ns和9.5 ns；等离子体碰撞分界线偏向于表面绝缘一侧,滞止时形成的磁流体不稳定性结构类似.%A laser shadowgraphy system was built based on a Nd:YAG laser backlight with a half width of 9 ns and a wavelength of 532 nm. It has the capacity of time resolution and integration simultaneously during the laser lighting time by utilizing a streak camera and a commercial digital camera as the image recording devices. Experimental study of the insulated-ordinary mixed planar wire array Z pinches was carried out on the Qiangguang-I facility. Experimental results indicate that the expansion of corona plasma of the insulated tungsten wires is slower than that of ordinary wires over the ablation stage. Average velocities of the insulated wire and the ordinary wire located at the array outmost edge are 1.1 × 104 m·s−1 and 1.7 × 104 m·s−1 between t=44 ns and t=56 ns respectively. In the fastest implosion stage of 10 ns just before the stagnant time, the average imploding velocities were 5.5 × 105 m·s−1 and 9.3 × 105 m·s−1 respectively for the plasma on the insulted wires side and the ordinary wires side. The duration of stagnant stage on the insulated wires side is 5.9 ns, while it is 9.5 ns on the ordinary wires side. The collision boundary is deflected to the insulated wires side. A similar magneto Rayleigh-Taylor Instability structure can be observed on the both sides at the stagnant time.