title: Measurement of radial profiles of density ratio of helium to hydrogen ion using charge exchange spectroscopy with two-wavelength spectrometer.
abstract: Radial profiles of density ratio of helium to hydrogen ions are measured using the charge exchange spectroscopy technique with the two-wavelength spectrometer system in the large helical device. The two-wavelength spectrometer system consists of a dichroic mirror box, a spectrometer with two grating and two camera lenses, and one CCD detector. The dichroic mirror box is used to divide the light of one fiber from the plasma to two fibers, one for HeII (λ = 468.6 nm) and the other for H(α) (λ = 656.3 nm), that are connected to the entrance slit of the spectrometer to eliminate the interference between the HeII and the H(α) spectra on the CCD. This system provides a simultaneous measurement of helium and hydrogen ion density ratio at 8 exact same locations (8 spatial channels) with a time resolution of >40 ms in the wide range of the density ratio of 0.05-5.
authors.affiliation: National Institute for Fusion Science, Toki 509-5292, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ida
authors.affiliation: National Institute for Fusion Science, Toki 509-5292, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yoshinuma
authors.affiliation: National Institute for Fusion Science, Toki 509-5292, Japan.
authors.forename: B
authors.initials: B
authors.lastname: Wieland
authors.affiliation: National Institute for Fusion Science, Toki 509-5292, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Goto
authors.affiliation: National Institute for Fusion Science, Toki 509-5292, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: National Institute for Fusion Science, Toki 509-5292, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: National Institute for Fusion Science, Toki 509-5292, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Murakami
authors.affiliation: National Institute for Fusion Science, Toki 509-5292, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Moon