R&D´s on negative ion source and accelerator for high energy NBI

Recent activities on negative ion source R&D at JAERI (Japan Atomic Energy Research Institute) are presented. After succeeding in the production of a 10 A H^- beam, negative ion source, R&D has progressed in two directions. The first direction is long pulse operation of a Cs seeded volume source. Continuous operation for 1000 s was achieved, producing an H^- beam of 50 keV and 0.52 A (14 mA/cm²). It was confirmed that the heat load in the ion source was at a tolerable level for continuous operation. Through a 24 h continuous operation, it was proved that cesium consumption was at a quite low rate of less than 4 mg/h. The second research direction is high energy acceleration. An H^- acceleration experiment has been performed in a conventional electrostatic accelerator with a single beam aperture. From a Cs seeded volume production source, a high energy H^- beam of 300 keV, 17 mA was produced for 5 s by a two-stage electrostatic accelerator with a good beam quality