title: Beam emission spectroscopy with radially and poloidally elongated optical sightlines.
abstract: Beam emission spectroscopy is widely used as local density fluctuation measurement of fusion plasmas. We have installed a beam emission spectroscopy system in the large helical device (LHD) with radially and poloidally elongated optical configuration to enhance both signal-to-noise ratio and wavenumber sensitivity in radial and poloidal directions. The calculation considering the integral effect of the line of sight showed the radially and poloidally elongated sightlines have increased sensitivity compared with the square shaped bundle design of the same sampling area.
authors.affiliation: Department of Fusion Science, SOKENDAI (The Graduate University for Advanced Studies), Toki, Gifu 509-5292, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ono
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ida
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yoshinuma
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kisaki
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nakano
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Moon