Application of a self-breakdown hydrogen spark gap switch on high power pulse modulator

Abstract

Hydrogen has the best recovery property compared with other gases such as N2 and SF6, which has a potential application on the multi-pulse and high repetitive pulse modulator. This paper introduced a high pressure hydrogen gas switch with two cylindrical structures. The stress of the switch under high pressure is analyzed theoretically, and the pressure of hydrogen gas in the switch was hydrostatically tested up to 30atm. Such a switch was employed on high power pulse modulator with water dielectric PFL (Pulse Forming Line). At the switch breakdown voltage of 520kV and the pressure of hydrogen 12atm, a 230kV, 31kA and 60ns during time electron beam is obtained at the field-emission diode. Furthermore, when the switch was filled in different gases such as H2, N2, SF6, the rise times of diode voltage of modulator have been compared at the switch breakdown voltage 400kV. The results show that the rise times of diode voltage is reduced obviously when hydrogen is used as the dielectric of spark gap switch.