Fast magnet power supplies for dynamic proton beam control for tumor treatment

A new tumor treatment facility is currently under construction at the Paul Scherrer Institute, Switzerland. The treatments are performed by actively scanning a three dimensional target volume, the tumor, with a thin proto In beam, depositing a defined energy dose. To allow multiple rescanning of moving target volumes without increasing the treatment time, the proton beam is deflected rapidly and independently in two directions by means of dipole magnets. For that purpose, two highly dynamic magnet power supplies were developed and commissioned. This paper describes the requirements, some design considerations and the test results of these power supplies.