激光触发火花间隙开关的触发机理与实验性能研究

Study on the Triggering Mechanism and Experimental Performance of Laser-Triggered Spark Gap Switches

摘要: 激光触发火花间隙开关具有延时短、抖动低、同步性能好等优点，是磁惯性约束聚变中同轴等离子体枪的核心部件。本文系统研究了该开关的触发机理、实验平台及性能表征方法。基于气体放电理论，分析了激光场电离替代随机本底辐射产生初始电子的物理机制。搭建了以Nimma-600激光器、30 kV高压电源及罗氏线圈为核心的实验平台，采用尖–平板钨电极结构和高密度聚乙烯腔体。在氩气和氮气环境下开展了系统实验，研究了激光波长、能量、气压和电压对开关延时与抖动的影响。结果表明：在氩气环境下，开关抖动可控制在30 ns以内；在氮气环境下，采用532 nm激光(100 mJ)时，开关在0.6 bar、15 kV条件下的抖动低至14.22 ns。随着激光能量增加，开关延时与抖动均减小，但存在一定的饱和效应；气压升高会导致延时与抖动增大。本文研究结果可为多路同步触发技术及同轴等离子体枪的工程应用提供技术支撑。

Abstract: Laser-triggered spark gap switches offer advantages such as short delay times, low jitter and excellent synchronization performance. This makes them a core component of coaxial plasma guns used in magnetic inertial confinement fusion. This paper systematically investigates the triggering mechanism, the experimental platform and the performance characterization methods of this switch. Based on gas discharge theory, the physical mechanism by which laser field ionization replaces random background radiation to generate initial electrons is analyzed. An experimental platform centered on a Nimma-600 laser, a 30 kV high-voltage power supply and a Ross coil was constructed, utilizing a pointed-flat tungsten electrode structure and a high-density polyethylene chamber. System experiments were conducted in argon and nitrogen atmospheres to investigate the effects of laser wavelength, energy, gas pressure and voltage on switch delay and jitter. The results indicate that, under argon conditions, switching jitter can be controlled to within 30 ns. Under nitrogen conditions and using a 532 nm laser (100 mJ), switching jitter was found to be as low as 14.22 ns at 0.6 bar and 15 kV. As laser energy increases, both switching delay and jitter decrease, though a saturation effect is observed at a certain point. An increase in gas pressure leads to increased delay and jitter. The findings of this study provide technical support for the engineering applications of multi-channel synchronous triggering technology and coaxial plasma guns.