Status of a 140KV/50HZ IGBT Marx modulat

CEA is working on a solid state pulse modulator to drive an electron gun, source of an RF accelerator. The application requires square pulses in the range of 140kV (1% flat top), 10A, 150μs width, at a repetition rate of 50Hz and a reproducibility pulse-to-pulse better than 10^-3. This modulator is based on a Marx topology which employs standard 1700V IGBTs and diodes to control the charge, discharge and isolation of the cells. This topology is of particular interest in reducing size and cost and increasing reliability. It has also the main advantage of transformerless operation. First experiments are detailed in this paper. 150μs pulses up to 40kV were obtained at a repetition rate of 50Hz on a resistive load. Pulse shapes can be fitted to the application (slowing down of rise and fall times for instance). Shortcircuit protections have been implemented to protect the load and the modulator.