title: Effects of filament geometry on the arc efficiency of a high-intensity He+ ion source.
abstract: A strongly focusing high-intensity He(+) ion source equipped with three concave electrodes has been designed and constructed as the beam source for a high-energy He(0) neutral beam probe system to diagnose fusion-produced alpha particles in thermonuclear fusion plasmas. The reduction of heat load onto the concave extraction electrodes is particularly important for a long pulse operation, as the heat load deforms the electrodes and thus the beam focal length. The effects on the arc efficiency (beam current/arc power) of the ion source due to the discharge filament structure (straight-type and L-shape-type filaments), size (filament diameters of 2 and 1.5 mm), number, and the locations have been studied. Choice of the appropriate filament structure improved the arc efficiency by 17%.
authors.affiliation: School of Engineering, Tohoku University, Sendai 980-0579, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kobuchi
authors.forename: M
authors.initials: M
authors.lastname: Kisaki
authors.forename: K
authors.initials: K
authors.lastname: Shinto
authors.forename: A
authors.initials: A
authors.lastname: Okamoto
authors.forename: S
authors.initials: S
authors.lastname: Kitajima
authors.forename: M
authors.initials: M
authors.lastname: Sasao
authors.forename: K
authors.initials: K
authors.lastname: Tsumori
authors.forename: O
authors.initials: O
authors.lastname: Kaneko
authors.forename: H
authors.initials: H
authors.lastname: Sakakita
authors.forename: S
authors.initials: S
authors.lastname: Kiyama
authors.forename: Y
authors.initials: Y
authors.lastname: Hirano
authors.forename: M
authors.initials: M
authors.lastname: Wada