Development of a high-precision power supply for bending electromagnets of a heavy ion medical accelerator

A 3 MW-class high-precision IGBT chopper type power supply was developed for the bending electromagnets of the Heavy-Ion Facility at Gunma University. The current ripple was smaller than ±1×10
^-5
, and the current tracking error was smaller than ±1×10
^-4
. Heavy ion beams were successfully accelerated with this power supply, and medical treatment commenced on 16th March 2010.