Plasma and Fusion Research

Volume 11, 1402115 (2016)

Regular Articles

Measurement of Spatiotemporal Structures of Density Fluctuations Using Two-Directional Beam Emission Spectroscopy in LHD
Makoto ONO, Katsumi IDA1), Mikirou YOSHINUMA1), Haruhisa NAKANO1), Tatsuya KOBAYASHI1) and Chanho MOON2)
Department of Fusion Science, School of Physical Sciences, SOKENDAI (The Graduate University for Advanced Studies), Toki, Gifu 509-5292, Japan
1)
National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
2)
Max-Planck-Institut für Plasmaphysik, EURATOM Association, 85740 Garching, Germany
(Received 6 January 2016 / Accepted 26 May 2016 / Published 5 October 2016)

Abstract

A beam emission spectroscopy (BES) system for density fluctuation measurements having the sight lines passing through the plasma in the toroidal direction was developed in the Large Helical Device (LHD). The coverage of the area sampled by 15 × 100 optical fibers is nearly from the core to the edge on the horizontally elongated poloidal cross section with the spatial pitch of around 1.0 cm, and 32 channels is detected simultaneously with the 4 × 8 pixel Avalanche Photodiode Detector camera. In order to improve the directional sensitivity for the propagation of the density fluctuation in the radial direction or the poloidal direction, we propose the use of slit-shaped sight lines. An initial result of the density fluctuation measurements for MHD activity in the edge region and its cross-correlation analysis is presented.

Keywords

plasma diagnostic, beam emission spectroscopy, density fluctuation, magnetohydrodynamics, Large Helical Device

DOI: 10.1585/pfr.11.1402115

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