title: Neutral beam injection with an improved accelerator for LHD.
abstract: The beam profiles, port-through, rates and injection powers obtained with an improved accelerator with the multislot grounded grid are described. The accelerator has a combination of a steering grid with racetrack shaped aperture and multislot grounded grid to improve the beam optics. The optimal beam optics is obtained at the voltage ratio of 16.5-16.8, and the profiles are well fit by superposing multibeamlets with the divergent angles of 5.0 and 7.2 mrad along the direction parallel to the long and short axes of the slots of grounded grid. By adopting the racetrack shaped steering grid, the port-through rate increases from 34% to 38%, and the maximum injection power reaches 6 MW/187 keV.
authors.affiliation: National Institute for Fusion Science, Gifu, Japan. tsumori@nifs.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Tsumori
authors.forename: M
authors.initials: M
authors.lastname: Osakabe
authors.forename: O
authors.initials: O
authors.lastname: Kaneko
authors.forename: Y
authors.initials: Y
authors.lastname: Takeiri
authors.forename: K
authors.initials: K
authors.lastname: Nagaoka
authors.forename: Y
authors.initials: Y
authors.lastname: Oka
authors.forename: K
authors.initials: K
authors.lastname: Ikeda
authors.forename: M
authors.initials: M
authors.lastname: Shibuya
authors.forename: E
authors.initials: E
authors.lastname: Asano
authors.forename: S
authors.initials: S
authors.lastname: Komada
authors.forename: T
authors.initials: T
authors.lastname: Kondo
authors.forename: M
authors.initials: M
authors.lastname: Sato