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Survey of EUV Impurity Line Spectra and EUV Bremsstrahlung Continuum in LHD

Chunfeng DONG, Shigeru MORITA¹⁾, Malay Bikas CHOWDHURI²⁾ and Motoshi GOTO¹⁾

Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu, Japan

1)

National Institute for Fusion Science, Toki 509-5292, Gifu, Japan

2)

Institue for Plasma research, Bhat, Gandhinagar 382428, Gujarat, India

(Received 5 January 2011 / Accepted 14 February 2011 / Published 12 July 2011)

Abstract

Radial profiles of impurity spectral line emissions in extreme ultraviolet (EUV) range (60-400 Å) are surveyed for impurity seeded discharges in Large Helical Device (LHD). The line emissions from light impurities such as helium, carbon and neon are located in the edge ergodic layer (1.0 ≤ ρ ≤ 1.2) except for CV and CVI, which are located in region of 0.8 ≤ ρ ≤ 1. In contract, the line emissions from heavy impurities such as iron are widely located over the whole plasma region as a function of ionization energy. On the other hand, the radial profile of bremsstrahlung continuum radiation is also clearly recorded in the EUV spectrum observed from high-density discharges with hydrogen pellet injection. Wavelength intervals available for the absolute sensitivity calibration of the present space-resolved EUV spectrometer system are listed with dominant line emissions which are useful as a wavelength marker.

Copyright (c) 2011 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

EUV spectra, radial profile, light impurity, heavy impurity, bremsstrahlung continuum

DOI: 10.1585/pfr.6.2402078

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This paper may be cited as follows:

Chunfeng DONG, Shigeru MORITA, Malay Bikas CHOWDHURI and Motoshi GOTO, Plasma Fusion Res. 6, 2402078 (2011).