High-energy and high-current hydrogen negative-ion beam production with an external-filter-type large negative-ion source

Journal Article · Fri Mar 01 04:00:00 EST 1996 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.1146744· OSTI ID:279231

Takeiri, Y; Kaneko, O; Oka, Y; Tsumori, K; Asano, E; Akiyama, R; Kawamoto, T; Kuroda, T ^[1]; Ando, A ^[2]

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1. National Institute for Fusion Science, Nagoya 464-01 (Japan)
2. Faculty of Engineering, Tohoku University, Sendai 980-77 (Japan)

A large hydrogen negative-ion source with an external magnetic filter has been developed for a neutral beam injection (NBI) system in the Large Helical Device (LHD), and a high-energy and high-current H{sup {minus}} ion beam has been produced. The ion source is operated at a high arc efficiency of 0.1 A/kW at an operational gas pressure of less than 3.5 mTorr, and produces 47 keV{endash}16.2 A of a H{sup {minus}} ion beam from a grid area of 25 cm{times}50 cm. With two-stage acceleration, 13.6 A of a H{sup {minus}} ion beam has been successfully accelerated to 125 keV. Multibeamlet focusing by the aperture displacement technique has been achieved 11.2 m downstream with a gross divergence angle of 9 mrad. The alternate beamlet deflection by the magnetic field at the extraction grid, which results in beam broadening in the deflection direction, was well compensated also by the aperture displacement technique. These results satisfy the specification of the negative-ion-based LHD{endash}NBI system. {copyright} {ital 1996 American Institute of Physics.}

• OSTI ID: 279231
• Report Number(s): CONF-9509125--
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 3 Vol. 67; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

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