Regular Articles

Full Text / References

Measurement and Analysis of Visible Line Spectra with Inhomogeneous Spatial Distribution in LHD

H. YAMAZAKI, M. GOTO¹⁾, S. MORITA¹⁾, T. H. WATANABE¹⁾ and LHD experimental group

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

1)

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

(Received 4 December 2006 / Accepted 30 March 2007 / Published 20 November 2007)

Abstract

Spatially resolved spectra have been measured with visible spectroscopy in Large Helical Device (LHD). Strong line emissions of H I, He I and C III have been observed at a limited area near the inboard-side X-point. Such a poloidally inhomogeneous radiation structure is drastically changed when the radius of the magnetic axis is shifted from R_ax = 3.6 m to 3.9 m: another strong emission emerges near the outboard-side X-point. In order to understand the physical mechanism the electron temperature and density are evaluated from intensity ratios of neutral hydrogen and helium lines at poloidal locations near both the X-points and at the bottom O-point edge. It is found that the changes of the electron temperature and density along the poloidal direction are too moderate to explain the inhomogeneity of line emissions for both the configurations. The present result suggests that the poloidal inhomogeneity of neutral emissions arises owing to the inhomogeneous neutral density distribution rather than the difference of the electron density or temperature.

Copyright (c) 2007 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

visible spectra, inhomogeneous profile, Hα, He I, line intensity ratio

DOI: 10.1585/pfr.2.S1115

Full Text

PDF format (560Kbytes)

References

• [1] M. Goto and S. Morita, Phys. Rev. E 65, 026401 (2002).
• [2] S. Morita, M. Goto et al., Physica Scripta T91, 48 (2001).
• [3] B. Schweer, G. Mank, A. Pospieszczyk et al., J. Nucl. Mater. 196-198, 174 (1992).
• [4] M. Goto, JQSRT 76, 331 (2003).
• [5] S. Masuzaki, T. Morisaki, M. Shoji et al., Fusion Sci. Tech. 50, 316105 (2006).
• [6] T. Morisaki, S. Masuzaki, M. Goto, S. Morita et al., Contrib. Plasma Phys. 42, 321 (2002).
• [7] T. Fujimoto and S.M. atsumoto, Nucl. Fusion 28, 267 (1988).

This paper may be cited as follows:

H. YAMAZAKI, M. GOTO, S. MORITA, T. H. WATANABE and LHD experimental group, Plasma Fusion Res. 2, S1115 (2007).