Fourth generation switching power supply for circular induction accelerators

Abstract

A switching power supply (SPS) was applied as the high-frequency bipolar high-voltage pulse source required to accelerate charged particles in the induction synchrotron, which was a novel synchrotron proposed at the High Energy Accelerator Research Organization (KEK) in 2006, and it was also used in other circular induction accelerators proposed thereafter, including the induction sector cyclotron and the induction microtron. As the heart of the circular induction accelerator, the SPS has recently been developed up to a fourth generation system that uses newly developed 3.3 kV high-speed SiC metal–oxide–semiconductor field-effect transistors(MOSFETs). The updates involved in this new SPS include the use of two parallel MOSFETs in each arm to shunt heat dissipation at high frequencies, optimization of the bus pattern, with low parasitic capacitance among the arms to improve the drain–source voltage (VDS) balance, and addition of current sampling circuits to provide an economical method to monitor the operating status in large-scale application scenarios. The heat power and temperature characteristics of the MOSFETs were studied specifically in both individual tests and SPS tests. To date, the new SPS has achieved 2.5 kV-17.4 A bipolar output at 350 kHz in continuous mode operation. The highest junction temperature of the MOSFETs was estimated to be 98 °C.

Effective DC acceleration of charged particles in a circular ring and its potential application

“…Further, four relatively small ceramic plates with a brazed joint to other metal rods, both ends of which are connected to the upstream/downstream beam pipe, are located near the beam pipe on the front cell plate. Electrical conduction in all the metal rods is controlled by active switching elements such as SiC-MOSFETs with a high withstand voltage 7 . CST Studio simulations 8 show that geometrically symmetric short circuits are important for field uniformity within the induction cell.…”