Acceleration of ampere class H ion beam by MeV accelerator

MeV級加速器によるアンペア級負イオンビーム加速

谷口 正樹; 井上 多加志; 梅田 尚孝; 柏木 美恵子; 渡邊 和弘; 戸張 博之; 坂本 慶司; 大楽 正幸

Taniguchi, Masaki; Inoue, Takashi; Umeda, Naotaka; Kashiwagi, Mieko; Watanabe, Kazuhiro; Tobari, Hiroyuki; Sakamoto, Keishi; Dairaku, Masayuki

The H accelerator R&D to realize the ITER NB is on going at JAEA. Up to 2005, 836 keV, 146 A/m H beam was successfully accelerated, as the highest record of the current density at MeV class energy beams. In the present work, high current negative ion beam acceleration test was performed by increasing the beam extraction apertures from 33 to 44. The highest H current of 322 mA was obtained at the energy of 753 keV. The acceleration of H beam of this level was repeated for a dozens of shots. After the high current density H ion beam acceleration above, performance of the KAMABOKO negative ion source degraded with fewer enhancements in negative ion current density under the Cs seeded condition. This was due to air leaks by high power loadings on the KAMABOKO source by the backstream positive ions. The paper reports the ion source operation in such high power negative ion beam acceleration with an estimate of heat loading by the backstream positive ions.