Compact semiconductor-based Marx generator design for microsecond pulsed electron beam devices

Summary form only given. For microsecond pulsed electron beam facilities with explosive emission cathodes a new semiconductor-based generator has been develop. This novel design concept comprises a unipolar Marx configuration, which is designed for a rectangular voltage of 120 kV and a maximum current of 150 A at a pulse length of up to 50 microsecond. A fast rise of the voltage within less than 100 ns is required to foster an instantaneous plasma generation at the cathode. Hence, fast switching is necessary. The paper describes aspects of the design of the semiconductor-based pulse generator. The charging path of the circuit comprises diodes in the ground-side branch and IGBTs in the high-voltage side branch. This connection also results in a parallel configuration of the capacitors during charging. For pulse generation the capacitors are switched in series such, that the polarity of the pulse is inverted with respect to the charging voltage. With such circuit a rectangular pulse can be generated, if the switches are capable of breaking the current and the stage capacitors are chosen large enough that the voltage droops due to discharge is negligible. Keeping the voltage constant should prevent cathode plasma from bridging the acceleration gap.