[Table of Contents]

Plasma and Fusion Research

Volume 2, S1060 (2007)

Regular Articles

Line analysis of EUV Spectra from Molybdenum and Tungsten Injected with Impurity Pellets in LHD
Malay Bikas CHOWDHURI, Shigeru MORITA1), Motoshi GOTO1), Hiroaki NISHIMURA2), Keiji NAGAI and Shinsuke FUJIOKA2)
Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Japan
1)
National Institute for Fusion Science, Toki 509-5292, Japan
2)
Institute of Laser Engineering, Osaka University, Suita 565-0871, Japan
(Received 4 December 2006 / Accepted 14 March 2007 / Published 20 November 2007)

Abstract

Spectroscopic data on high-Z materials for impurity diagnostics are important due to its possible use as a plasma facing component in the next generation fusion device. For this purpose molybdenum and tungsten are injected by an impurity pellet injector into the large helical device (LHD) plasmas. Emissions from such highly ionized elements mostly fall in extreme ultraviolet (EUV) and soft X-ray ranges. The EUV spectra in a range of 20-500 Å are recorded using a flat-field EUV spectrometer. The observed emissions are identified with the help of its temporal evolution and detailed analysis is done with electron temperature profiles. At high central electron temperature (∼2.2 keV) molybdenum appears as an Al-, Mg- and Na-like ionization stages. Typical examples of identified transitions are Mo XXXI 190.46 Å (3 s2 1S-3s3p 3P) and Mo XXXII 176.63 Å (3s 2S-3p 2P). For tungsten, on the other hand, three well-separated bands appear in wavelength range of 24-80 Å. The transitions around 33 Å have been tentatively identified with the help of calculated values. Most of the isolated lines on the top of pseudo-continuum bands around 50 and 60 Å are identified, and the wavelengths are compared with previous experimental studies and also with calculated values.

Keywords

EUV spectra, metallic impurity, Mo, W

DOI: 10.1585/pfr.2.S1060

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This paper may be cited as follows:

Malay Bikas CHOWDHURI, Shigeru MORITA, Motoshi GOTO, Hiroaki NISHIMURA, Keiji NAGAI and Shinsuke FUJIOKA, Plasma Fusion Res. 2, S1060 (2007).