Development of 1 MeV accelerator for ITER; Achievement of 0.98 MeV, 185 A/m negative ion beam acceleration

Kashiwagi, Mieko; Taniguchi, Masaki; Umeda, Naotaka; Dairaku, Masayuki; Takemoto, Jumpei; Tsuchida, Kazuki; Tobari, Hiroyuki; Yamanaka, Haruhiko; Watanabe, Kazuhiro; Sakamoto, Keishi; Inoue, Takashi

In a MeV accelerator test for the ITER neutral beam injector (NBI), beam acceleration tests are progressed toward 1 MeV, 200 A/m H ion beams. As results of suppression of breakdowns due to local electric field concentrations and suppression of direct interception of deflected beamlets due to magnetic field and space charge repulsion, the beam parameters increased from 0.8 MeV to 0.98 MeV, 185 A/m. This is achieving the target value. After this achievement, the results of the MeV accelerator are applied to the ITER accelerator design.