Research on Current-Rise Rate During Closing Process of Laser-Triggered Vacuum Switch

The plasma development characteristics of laser-triggered vacuum switch (LTVS) have an effect on the current-rise rate when a pulsed-power system releases energy to the load. The current-rise rate is an important performance parameter for the evaluation of LTVS. In this article, the plasma impedance parameters during LTVS closing process are analyzed theoretically. The mathematical expressions of current are obtained with the equivalent circuit. Furthermore, LTVS closing experiments are carried out under different laser energy, operating voltage, gap distance, and electrode structure. Theoretical analysis and experimental results show that the current-rise rate is determined by the plasma time-varying resistance and time-varying inductance under certain external circuit conditions. The high current-rise rate can be obtained by enhancing laser energy, increasing operating voltage, shortening gap distance, or using axial magnetic field (AMF) electrodes. Remarkably, increasing laser energy or using AMF electrodes will lead to a sharp current fluctuation, resulting in overvoltage during closing process.