[Table of Contents]

Plasma and Fusion Research

Volume 5, S1033 (2010)

Regular Articles

Spectroscopic Diagnostics for Spatial Density Distribution of Plasmoid by Pellet Injection in the Large Helical Device
Gen MOTOJIMA, Ryuichi SAKAMOTO, Motoshi GOTO, Hiroshi YAMADA and LHD experiment group
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
(Received 1 February 2009 / Accepted 21 June 2009 / Published 26 March 2010)

Abstract

To investigate the behavior of a plasmoid consisting of pellet ablatant ionized by background plasma, two dimensional imaging measurements of high-speed spectroscopy have been developed using a fast camera in the Large Helical Device (LHD). The diagnostic system provides density distribution of the plasmoid. The density distribution is determined using the Stark broadening width of the Balmer-β line. Stark broadening profile can be evaluated from the intensity ratio measured using narrow-band optical filters having different full width at half maximum. Two dimensional images of the plasmoid are obtained by a fast camera connected to a bifurcated fiber scope with two objective lenses. An initial result shows that the plasmoid density is obtained within a factor of 2 by imaging measurements.

Keywords

pellet injection, plasmoid, imaging measurement, spectroscopy, LHD, helical device

DOI: 10.1585/pfr.5.S1033

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References

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This paper may be cited as follows:

Gen MOTOJIMA, Ryuichi SAKAMOTO, Motoshi GOTO, Hiroshi YAMADA and LHD experiment group, Plasma Fusion Res. 5, S1033 (2010).