title: Up-down asymmetry measurement of tungsten distribution in large helical device using two extreme ultraviolet (EUV) spectrometers.
abstract: Two space-resolved extreme ultraviolet spectrometers working in wavelength ranges of 10-130 Å and 30-500 Å have been utilized to observe the full vertical profile of tungsten line emissions by simultaneously measuring upper- and lower-half plasmas of LHD, respectively. The radial profile of local emissivity is reconstructed from the measured vertical profile in the overlapped wavelength range of 30-130 Å and the up-down asymmetry is examined against the local emissivity profiles of WXXVIII in the unresolved transition array spectrum. The result shows a nearly symmetric profile, suggesting a good availability in the present diagnostic method for the impurity asymmetry study.
authors.affiliation: Department of Fusion Science, Graduate University for Advanced Studies, Toki, Gifu 509-5292, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Fusion Science, Graduate University for Advanced Studies, Toki, Gifu 509-5292, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Morita
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: X L
authors.initials: XL
authors.lastname: Huang
authors.affiliation: Department of Fusion Science, Graduate University for Advanced Studies, Toki, Gifu 509-5292, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Oishi
authors.affiliation: Department of Fusion Science, Graduate University for Advanced Studies, Toki, Gifu 509-5292, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Goto
authors.affiliation: Department of Fusion Science, Graduate University for Advanced Studies, Toki, Gifu 509-5292, Japan.
authors.forename: H M
authors.initials: HM
authors.lastname: Zhang