Self-breakdown stability of gas switch based on high-energy runaway electron mechanism

To achieve precise control of the main triggered switch of the pulsed power source, a triggered gas switch based on the principle of corona stabilization was developed. The process of stabilized corona discharge and the influence of high-energy runaway electrons on the stability of breakdown were analyzed. This study also revealed the mechanism by which suppressing high-energy runaway electrons was beneficial in increasing the stability of gas switch self-breakdown. The experimental study was carried out from the perspectives of gas medium and E-field conditions, and the self-breakdown stability of the gas switch was compared. The self-breakdown dispersion of the gas switch filled with 15% SF₆/N₂ mixed gas was no more than 6% within the pressure of 0.06 MPa to 0.56 MPa, while the lowest value was 1.4%. The self-breakdown voltage dispersion remained within the range of 2%-4% when the electrically negative gas content in the SF₆/N₂ mixed gas was less than 30%. Within the charging voltage range of less than 1800 V, by changing the time-domain variation speed of the E-field in the gap, the self-breakdown voltage dispersion could be reduced to 0.2% with the breakdown voltage of 242 kV, while the voltage on the high voltage electrode rising speed was 12.4 kV/μs. However, reducing the field non-uniform coefficient didn`t significantly improve the breakdown stability in the 15% SF₆/N₂ mixed gas at 0.3 MPa, but the self-breakdown voltage dispersion was still kept below 1% when the voltage rising speed increased on the high voltage electrode. By replacing the wedge-shaped trigger electrode with a groove-shaped trigger electrode, the minimum self-breakdown voltage dispersion could be as low as 0.15%, and the breakdown voltage was stabilized around 248 kV.