Investigations on Trigger Process of Triple-Gap Laser Triggered Multi-Stage Vacuum Switch

Abstract

To develop high voltage pulsed power closing switch utilizing the advantages of vacuum gap, a laser triggered multi-stage vacuum switch (LTMVS) is proposed in this paper. Trigger processes of triple-gap LTMVS are analyzed based on a detachable vacuum chamber. Closing processes and time-delay characteristics of different sections in LTMVS are studied later. The results convey that, trigger process of LTMVS can be separated to two periods, the trigger of laser triggered gap and the cascade breakdown of series connected vacuum gaps. Breakdown sequences of cascade gaps are unstable, and its delay time mainly depends on the initially breakdown gap. The increase of laser energy and operating voltage benefit to both reducing the delay time of triggered gap and cascade gaps. Under 30mJ laser energy, delay time of 4mm laser triggered gap can be controlled within 25.8±1.3ns, and breakdown delay time of 0.8mm vacuum gap reaches 79±2.5ns under impulse voltage with DC superimposition. Suggestions for the developments of LTMVS are given based on above researches.

Keywords: laser trigger, vacuum breakdown, vacuum switch, delay time, initial plasma