Effect of Working Coefficient on Induced Breakdown Characteristics of Plasma-Triggered-Based Gas Gap Switch in Fast Bypass Conditions

Gas gap switch (GGS) has obvious advantages in fast bypass operation, quick response, simple structure, and strong controllability. The working coefficient (i.e., the ratio of the main gap working voltage to the steady-state breakdown voltage) of GGS is mainly affected by the working voltage, the main gap distance, the type of trigger gas, and the pressure. However, the research mostly focuses on the influence of the above single factors on the trigger performance of GGS. There is a lack of studies on the induced breakdown characteristics of GGS considering the variation of the working coefficient under different factors. In this article, a research platform about the induced breakdown of GGS is established. It is shown that the working process of the GGS trigger cavity is divided into the high voltage pulse prebreakdown stage in the first cavity, the discharge ablation stage in the first cavity, and the discharge ablation stage in the second cavity. With the increase of the working voltage, the critical trigger capacitor voltage is lower, and the plasma jet characteristic parameters are decreased gradually during the critical conduction. The conduction time delay and time delay jitter are decreased rapidly, the triggering stability is significantly improved. Changing the main gap distance, the discharge channel shape is a significant difference at the moment of GGS-induced breakdown. And the electric characteristics of plasma jets are varied obviously. The high trigger gas pressure hinders the development of the plasma jet and causes a greater trigger jitter. With the increase of SF6 content in the trigger environment, the characteristic parameters of GGS decrease obviously. The strong insulation and electronegative gas seriously constrain the plasma jet capability. The research results can provide theoretical guidance for the improvement of trigger stability and the selection of trigger condition parameters of plasma-triggered-based gas switches used in fast bypass conditions.