[Table of Contents]

Plasma and Fusion Research

Volume 5, S2099 (2010)

Regular Articles

Effect of Halo Neutrals on Fast-Ion Charge Exchange Spectroscopy Measurements in LHD
Takafumi ITO, Masaki OSAKABE1), Katsumi IDA1), Mikiro YOSHINUMA1), Masahiko KOBAYASHI1), Sadayoshi MURAKAMI2), Motoshi GOTO1), Yasuhiko TAKEIRI1), Detlev REITER3), Shoichi OKAMURA1) and LHD Experimental Group1)
The Graduate University for Advanced Studies, Toki 509-5292, Japan
1)
National Institute for Fusion Science, Toki 509-5292, Japan
2)
Department of Nuclear Engineering, Kyoto University, Kyoto 606-8501, Japan
3)
Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, D-52425 Juelich, Germany
(Received 22 December 2009 / Accepted 6 May 2010 / Published 10 December 2010)

Abstract

A fast-ion charge exchange spectroscopy (FICXS) diagnostic was recently installed on the Large Helical Device (LHD). The aim of this diagnostic is to evaluate fast-ion confinement property by measuring energy-resolved fast-ion spatial profiles in LHD. To accurately evaluate the FICXS profile, the effect of halo neutrals, which are created by the charge exchange between bulk ions and injected neutral beams (NBs), must be treated properly in the current analysis of the FICXS spectra in the LHD. We have estimated the effect of halo neutrals on the measurement from the shapes of Doppler-shifted H-alpha spectra. The ratio of halo neutrals to the injected NBs on the lines of sight (LOSs) is estimated by using the EIRENE-3D Monte Carlo code. The results of these two methods agreed well. This indicates that the effect of halo neutrals should be considered when interpreting the FICXS diagnostic data as well as that from the injected NB, when the probing NB is radially injected and the emitted photons are observed from perpendicular LOSs.

Keywords

fast-ion, charge exchange spectroscopy, neutral particle transport

DOI: 10.1585/pfr.5.S2099

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This paper may be cited as follows:

Takafumi ITO, Masaki OSAKABE, Katsumi IDA, Mikiro YOSHINUMA, Masahiko KOBAYASHI, Sadayoshi MURAKAMI, Motoshi GOTO, Yasuhiko TAKEIRI, Detlev REITER, Shoichi OKAMURA and LHD Experimental Group, Plasma Fusion Res. 5, S2099 (2010).