Solid-state high-voltage switching unit for accelerator applications

Solid-state high-voltage switching units are being developed for applications to power supplies of high-energy accelerators. The ultimate goal is to replace most of the traditional thyratron-based switching units for both present and future accelerators. Solid-state semiconductor power devices are advantageous in many respects such as lifetime, stability, maintenance, and cost. In this study, static-induction thyristor (SIThy) is selected as the switching device for the reason that it is faster than IGBT and is more powerful than MOSFET. A prototype SIThy-based switching unit has been made and tested for operation at 20 kV and 400 A. It consists of 10 SIThys connected in series. Detailed studies have been carried out on voltage balance and timing control, before this switching unit is put on a real accelerator for experimental evaluation. The KEK digital accelerator (KEK-DA), which is an induction synchrotron, requires a 20 kV pulser for its electrostatic injection kicker. This originally thyratrondriven pulse supply has been selected as the platform for the initial experimental demonstration of our SIThy switching unit. The results have proved that the solid-state switching unit is not only capable of replacing the traditional thyratronbased unit but also improves the performance of the pulsed high-voltage supply.