Research on Triggering Characteristics of Triple-Gap Laser Triggered Vacuum Switch

High-voltage laser-triggered vacuum switches have good application prospects in pulsed power systems. Laser-triggered vacuum switch (LTVS) is a new pulsed power closed switch that combines pulsed laser technology with vacuum switching technology. Compared with laser-triggered gas switches, laser-triggered vacuum switches can obtain similar or even better delay characteristics under the same conditions while avoiding a series of technical problems of gas switches. As the application areas of pulsed power technology continue to expand and system capacity grows, LTVS has the potential to become a switching device for high power applications. In this paper, a multi-gap laser-triggered vacuum switch is designed, including a laser-triggered gap and two symmetrical curling stainless steel electrodes in series. Based on the detachable vacuum chamber, a laser-triggered multi-gap vacuum switch test platform was built, and triggering characteristics of the multi-gap switch were experimentally studied under different laser energies, different operating voltages, and different voltage split ratios. The delay characteristics of the three-gap laser trigger switch are compared and analyzed, the main factors affecting the delay characteristics of the multi-gap series switch are explored, and the optimization design scheme of the working parameters of the high-performance multi-gap switch is obtained. The experimental results show that the trigger delay time of the multi-gap switch is not only related to the external working conditions, but also affected by the working parameters among the three gaps. With the increase of laser energy and operating voltage, the trigger delay and jitter time of the switch decrease. Better time-delay characteristics can be obtained by matching with appropriate working parameters. The on-trigger delay of the three-gap LTVS is determined by the on-delay of each gap and is mainly affected by the delay of its first self-breakdown gap. The remaining self-breakdown gap can be quickly turned on at a steeper impulse voltage. The voltage division ratio of each gap of the three-gap LTVS has a significant impact on the working delay of the switch, and the change of the voltage division ratio will change the rate of increase of the superimposed shock voltage during the trigger process, which will make the switch on rate different. When the laser energy and operating voltage are high, the trigger gap has a higher voltage division ratio, and the switching trigger performance is relatively good. The trigger delay of the three-gap LTVS gradually decreases with the increase of laser energy and operating voltage. That is, LTVS can obtain better trigger performance at higher laser energy and working voltage. The trigger-on characteristics of the three-gap laser trigger vacuum switch can be improved by increasing the laser energy and working voltage and changing the divider voltage ratio. The on-time delay of the three-gap LTVS can be controlled at (167±3) ns when the laser energy is 30 mJ, the operating voltage is 30 kV, and the partial voltage ratio is 4∶1∶1. This paper can lay the foundation for the study of high-performance laser-triggered multi-stage vacuum switches in higher voltage fields. © 2023 Chinese Machine Press. All rights reserved.