Status of ion sources for the Heavy Ion Medical Accelerator HIMAC

The Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences (NIRS) is the first heavy‐ion accelerator complex dedicated to cancer therapy. HIMAC is equipped with two kinds of ion sources. The PIG ion source is an indirectly heated cathode type, which is operated with a very low‐duty factor. The ECR ion source has a single closed ECR zone with 10 GHz microwaves. Both sources realize good stability and reproducibility with easy operation, and satisfy the requirements for radiotherapy. They have been successfully used for clinical trials since June of 1994, and several tens of cancer patients have already been treated with 290–400 MeV/u carbon beams.