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Indexed by:期刊论文

Date of Publication:2017-08-01

Journal:NUCLEAR MATERIALS AND ENERGY

Included Journals:Scopus、SCIE、EI

Volume:12

Issue:,SI

Page Number:762-767

ISSN No.: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.