Development of a high current H ion source for cyclotrons

Eto, Haruhiko*; Aoki, Yasushi*; Mitsubori, Hitoshi*; Arakawa, Y.*; Mitsumoto, Toshinori*; Yajima, S.*; Sakuraba, Junji*; Kato, Takanori*; Okumura, Yoshikazu

High current hydrogen negative ion source is required to increase the accelerated beam current of the cyclotrons for many medical applications such as cancer therapy and medical radioisotope production. A new negative ion source has been designed and fabricated. The ion source is a multi-cusp type. Optimization of the ion source is in progress, such as the optimization of the magnetic filter which prevents high temperature electrons from entering into the negative ion production region, improvement of the extraction electrode's shape and configuration of dipole magnets etc. A small quantity of Cs has been introduced into the ion source to enhance the negative ion beam current. The ion source produced 16mA of DC hydrogen negative ion beam with the Cs-seeded operation at a low arc discharge power of 2.8 kW.