title: Balmer-α spectrum measurements of the LHD one-third ion source.
abstract: Wavelength spectra of Balmer-α light from plasmas in the extraction region of the Large Helical Device-R&D negative ion source, or the LHD one-third ion source have exhibited a blue shift as a negative bias voltage was applied to the plasma grid. The blue shift increased as the negative bias voltage with respect to the local plasma potential was increased. The measured spectra were compared with the velocity distributions of surface reflected hydrogen atoms calculated by atomic collisions in amorphous target code. The arc power and the source H2 pressure also affected the shift and broadening in the observed Balmer-α spectra. The possibility of identifying the negative hydrogen ions produced at the low work function plasma grid surface by high resolution spectroscopy is discussed.
authors.affiliation: Graduate School of Science and Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Wada
authors.affiliation: School of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kenmotsu
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5202, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kisaki
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5202, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nakano
authors.affiliation: Graduate School of Frontier Science, The University of Tokyo, Kashiwa, 277-8561 Chiba, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nishiura
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5202, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tsumori