Investigation of the Impedance Characteristics During the Turn-On Process of Electrically Triggered Vacuum Surface Flashover Switches

Electrically triggered vacuum surface flashover switches (VSFSs) offer the advantages of rapid closure, high-pulsed repetition frequency, high reliability, and compact design for high pulse power technology. The output performance of the pulsed power system, as well as the lifetime of VSFS, is limited by the plasma impedance during the VSFS turn-on process. This article presents a theoretical calculation of the plasma impedance based on experimental measurements and second-order Taylor series, and the mathematical expressions of plasma impedance and ohmic loss are performed. From the experimental waveform and the theoretical calculation of the expression, the variation curve of the plasma impedance is derived. Finally, the influencing factors (operating voltage, loop resistor, discharge capacitor, trigger resistor, and trigger voltage) are investigated. The experimental results indicate that an increase in operating voltage can increase the plasma resistance drop rate and can reduce the plasma ohmic loss. The same trend is also achieved by decreasing the loop resistor. Moreover, the discharge capacitance, trigger voltage, and trigger current only affect the ON-state stage and the trigger process, and the impact on the plasma resistance and ohmic loss during the closing process is weak.