Study on Discharge Characteristics and Influence Laws of Sphere-Gap Isolation Trigger Gas Gap Switch Based on Marx Circuit

Gas gap switch breakdown is typically triggered by high-voltage pulses. Traditional pulse-variable isolation triggering methods are limited by magnetic saturation, compromising reliability. In contrast, the Marx circuit-based sphere-gap isolation trigger offers structural simplicity, reliable performance, and adjustable parameters for generating high-voltage pulses. This study investigates the influence of Marx circuit parameters, trigger cavity geometry, and gas medium on the gas gap switch’s discharge characteristics. Results show that induced breakdown involves high-speed plasma injection into the central gap. This forms an initial strong jet, which rapidly disperses into a weaker jet, ultimately causing the main gap breakdown. A short “spike” in arc current is observed, followed by slow attenuation. Optimal plasma-induced breakdown performance is achieved with a trigger cavity nozzle diameter of 1 mm and a surface height of 9 mm. High-voltage pulse parameters critically constrain the induced breakdown efficacy, while the gas medium significantly influences plasma jet dynamics (height and diameter). SF₆, a strongly electronegative gas, suppresses plasma jet development. These findings provide critical insights for optimizing high-voltage pulse-triggering circuits and gas gap switch design.