[Table of Contents]

Plasma and Fusion Research

Volume 6, 2402068 (2011)

Regular Articles

Development of Collective Thomson Scattering Diagnostic for Bulk and Fast Ions in the Large Helical Device
Masaki NISHIURA, Shin KUBO, Kenji TANAKA, Namiko TAMURA1), Takashi SHIMOZUMA, Takashi MUTOH, Kazuo KAWAHATA, Tetsuo WATARI, Teruo SAITO2), Yoshinori TATEMATSU2) and LHD Experiment Group
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
1)
Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
2)
FIR FU, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
(Received 28 December 2010 / Accepted 1 March 2011 / Published 1 July 2011)

Abstract

The collective Thomson scattering (CTS) technique has been utilized with the backscattering configuration to diagnose the bulk and fast ions in the Large Helical Device (LHD). The spectrogram of the scattered radiation presents the transient phenomena related to fast ion slowing down in auxiliary neutral beam heated plasmas. This is obtained by the broad band receiver resolving with 32 channels, while the probing beam from 77 GHz gyrotron is modulated with 50 Hz and is injected into plasmas. In the same shot, especially in low temperature plasma (Te, Ti < 1 keV), a wave excitation is also observed in a narrow frequency band. The peaks in the CTS spectrum exist between 0.5 and 1.0 GHz and are observed in both frequency sides asymmetry. For the forthcoming experiments, the feasibility of CTS diagnostics at a new port location is assessed to extend the diagnostic capability for measuring the ion velocity components. Expected spectra for scattered radiation are the same signal level as the present location from a numerical calculation.

Keywords

collective Thomson scattering, ion temperature, fast ion, velocity distribution function, fusion plasmas, lower hybrid wave

DOI: 10.1585/pfr.6.2402068

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This paper may be cited as follows:

Masaki NISHIURA, Shin KUBO, Kenji TANAKA, Namiko TAMURA, Takashi SHIMOZUMA, Takashi MUTOH, Kazuo KAWAHATA, Tetsuo WATARI, Teruo SAITO, Yoshinori TATEMATSU and LHD Experiment Group, Plasma Fusion Res. 6, 2402068 (2011).