Release Time:2019-03-13  Hits:

Indexed by: Journal Article

Date of Publication: 2017-08-01

Journal: NUCLEAR MATERIALS AND ENERGY

Included Journals: EI、SCIE、Scopus

Volume: 12

Issue: ,SI

Page Number: 762-767

ISSN: 2352-1791

Abstract: A space-resolved spectroscopy using a 3 m normal incidence vacuum ultraviolet (VUV) spectrometer was developed to measure the VUV emission profiles in wavelength range of 300-3200 angstrom from impurities in the edge plasmas in Large Helical Device (LHD). The edge plasma of the LHD is characterized by stochastic magnetic fields with three-dimensional structure intrinsically formed by helical coils called the "ergodic layer". The VUV spectroscopy has revealed that intensity profiles of the impurity emission from the ergodic layer have strong up-down asymmetries, namely, the emission intensities are quite different between top and bottom plasma edges. Observations of the up-down asymmetries are summarized on the following impurity line emissions: (1) CII 1335.71 angstrom (2s-2p), CIII 977.02 angstrom (2s-2p), and CIV 1548.20 angstrom (2s-2p) from intrinsic carbon impurity ions sputtered from the carbon divertor plates, (2) NeVII 465.22 angstrom (2s-2p), NeVIII 770.41 angstrom (2s-2p), ArVII 585.75 angstrom (3s-3p), and ArVIII 700.24 angstrom (3s-3p) from Ne or Ar ions introduced in plasmas by gas puffing, and (3) WVI 639.68 angstrom (5d-6p) from W ions introduced in plasmas by pellet injection. (C) 2017 The Authors. Published by Elsevier Ltd.