Wang Yu-Lin, Hu Guang-Yue, Hu Peng, Liang Yi-Han, Yuan Peng, Zheng Jian
CAS Key Laboratory of Geospace Environment and Department of Engineering and Applied Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
Rev Sci Instrum. 2019 Jul;90(7):075108. doi: 10.1063/1.5095541.
A portable pulsed magnetic field generator for magnetized laser plasma experiments in low vacuum environments is presented. It is based on a classical high-voltage discharge pulsed power system. A 95 kA peak current was delivered at a 65 kV discharge voltage, which generated a quasiuniform magnetic field of 12T in a Φ8 mm × 8 mm volume. A compact, sealed design was developed to avoid short-circuit breakdowns caused by an ambient low-pressure gas medium. Design improvements were made to the vacuum feedthrough, the transmission line, and the magnetic coil. The system worked well in a low vacuum environment for a laser plasma experiment using a gas target. But at intermediate ambient gas pressure, the ambient gas was ionized around the surface of the coil at first and then the ionized gas diffused inward and outward slowly, which affected the laser plasma image in the coil. Experiments and simulations indicated that the ambient gas was ionized by the induced electric field. We developed analytical models of the induced breakdown of the ambient gas to guide the experimental design of a gas target. The analysis can also be used in the experimental design of a solid target in an intense pulsed magnetic field of hundreds of tesla that the induced breakdown along solid's surface dominates the process.
介绍了一种用于低真空环境下磁化激光等离子体实验的便携式脉冲磁场发生器。它基于经典的高压放电脉冲电源系统。在65 kV放电电压下输出了95 kA的峰值电流，在Φ8 mm×8 mm的体积内产生了12T的准均匀磁场。开发了一种紧凑的密封设计，以避免由周围低压气体介质引起的短路击穿。对真空馈通、传输线和磁线圈进行了设计改进。该系统在低真空环境下对使用气体靶的激光等离子体实验运行良好。但在中等环境气体压力下，周围气体首先在线圈表面附近被电离，然后电离气体缓慢向内和向外扩散，这影响了线圈内的激光等离子体图像。实验和模拟表明，周围气体被感应电场电离。我们开发了周围气体感应击穿的分析模型，以指导气体靶的实验设计。该分析也可用于数百特斯拉强脉冲磁场中固体靶的实验设计，其中沿固体表面的感应击穿主导了该过程。
