title: Energy resolved soft x-ray imaging using a charge coupled device camera for long pulse discharges in the Large Helical Device.
abstract: Energy resolved soft x-ray imaging system using a charge coupled device camera and a multifilter disk has recently been installed to the Large Helical Device for the measurements in the long pulse discharges. Eight images with different cutoff energies are measured sequentially during a single discharge by rotating a filter disk mounting eight beryllium filters with different thicknesses. A tangential line-integrated profile for a specific photon energy range can be obtained by taking intensity difference between two images measured with a filter pair of adjacent thicknesses. The typical photon energy corresponding to each difference ranges from 1.9 to 4.8 keV with the bandwidth of 2-3 keV. In the initial results, the difference in the line-integrated soft x-ray profile by the energy range has been clearly observed. This diagnostic method can possibly be applied to the observation of the dependence of two dimensional soft x-ray profile on photon energy range especially if local non-Maxwellian component appears in electron energy distribution function.
authors.affiliation: National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Suzuki
authors.forename: K
authors.initials: K
authors.lastname: Ida
authors.forename: T
authors.initials: T
authors.lastname: Kobuchi
authors.forename: M
authors.initials: M
authors.lastname: Yoshinuma