Development of the National Institute of Radiological Sciences electron cyclotron resonance ion source for the heavy ion medical accelerator in Chiba Available to Purchase

The development of an electron cyclotron resonance ion source for the heavy ion medical accelerator in Chiba (HIMAC) injector is reported. The HIMAC is a heavy ion medical accelerator for cancer therapy. The electron cyclotron resonance (ECR) ion source is expected to provide a long lifetime, easy operation, and easy maintenance for medical use. The NIRS‐ECR ion source has a single closed ECR stage, and a microwave frequency of 10 GHz is applied. Under the present performance, the output electrical currents of the ions are 2500 eμA for He¹⁺, 300 eμA for C²⁺, 480 eμA for Ne³⁺, and 110 eμA for Ar⁶⁺. Stability of the intensity is better than 2%. The transmission efficiency through a low‐energy beam‐transport line with an acceptance of 200 πmm mrad is more than 70%; the typical 50% and 90% emittances of the injection beam with 8 keV/u are 20 and 80 πmm mrad, respectively. These performances satisfy the requirements for radiotherapy.