Study and development of Solid State based Long Pulse Klystron Modulators for future Linear Accelerators at CERN

Abstract

A new Klystron modulator is to be developed as a part of the new Linear Accelerator (LINAC4) project that is currently running at CERN. The Klystron modulator is required to supply a pulsed output voltage of -100 kV / 20 A with a repetition rate of 2 Hz and a pulse length of 800 us. In addition to this, the Klystron modulator must also handle arcing in the Klystron, and allow for no more than 10 J of energy to be dissipated in the arc in such a case. This thesis studies possible solid state based topologies that could be relevant for the Klystron modulator. A single switch topology, based on a 12 kV IGCT switch and a pulse transformer, is studied in detail and developed as a full scale prototype. Preliminary test results indicate that this will provide a satisfactory solution that meets the requirements. A second topology based on the Parallel Resonant Converter (PRC) was studied in detail through analysis and simulations. This showed to be a promising solution that could be an improvement compared to the single switch topology. The PRC is fully controllable and thus offers a flexible solution that can meet various demands. The topology also showed very good arc handling capabilities, and the PRC can be configured to protect the Klystron by its natural response.