Design considerations for a semiconductor-based Marx generator for a pulsed electron beam device

The pulsed electron beam device GESA modifies the surface of a metallic material by means of melting and subsequent cooling both at high temperature gradients. Heating of a thin surface layer is performed by applying an electron beam. In existing GESA devices a rectangular voltage is used for accelerating the electrons. It is delivered by LC-networks in Marx configuration. For a new GESA device a semiconductor-based pulse generator is being developed. This novel design concept for a GESA device 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 μs. 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 required. The paper describes aspects of the design of the semiconductor-based pulse generator.