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Preliminary Examination of Reflection Coefficient Measurement of RGB Lights on the First Wall in LHD

Gen MOTOJIMA, Naoaki YOSHIDA¹⁾, Takanori MURASE, Hirohiko TANAKA, Suguru MASUZAKI, Ryuichi SAKAMOTO, Masayuki TOKITANI, Kenji MATSUMOTO²⁾, Mitsutaka MIYAMOTO³⁾, Miyuki YAJIMA, Mizuki SAKAMOTO⁴⁾, Hiroshi YAMADA, Tomohiro MORISAKI and LHD Experiment Group

National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan

1)

Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga, Fukuoka 812-8580, Japan

2)

Honda R & D Co. Ltd., 4630 Shimotakanezawa, Haga-machi, Tochigi 321-3393, Japan

3)

Department of Material Science, Shimane University, Matsue, Shimane 690-8504, Japan

4)

Plasma Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan

(Received 2 June 2015 / Accepted 10 July 2015 / Published 25 September 2015)

Abstract

An innovative color measurement technique is employed in the Large Helical Device (LHD). This study provides a method for obtaining in broad spatial extent and in great detail the color information of the first wall relating to the thickness of the deposition layer. The RGB (Red, Green, and Blue) value, mainly of the stainless steel plates on the helically twisted coil, is measured by a color analyzer equipped with an integrated sphere light source. On the outer torus side, the colors of almost all stainless steel plates are close to carbon black, which suggests that deposition is dominant. On the inner torus side, all plates except for those neighboring the carbon divertor plates are almost white, as in the case of the stainless steel substrate of the first wall, which suggests that erosion is dominant. The relationship between the color and the distance from the stainless steel plates to the plasma is investigated.

Copyright (c) 2015 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

color measurement, wall retention, deposition layer, thickness, first wall, carbon, stainless steel

DOI: 10.1585/pfr.10.1202074

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References

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This paper may be cited as follows:

Gen MOTOJIMA, Naoaki YOSHIDA, Takanori MURASE, Hirohiko TANAKA, Suguru MASUZAKI, Ryuichi SAKAMOTO, Masayuki TOKITANI, Kenji MATSUMOTO, Mitsutaka MIYAMOTO, Miyuki YAJIMA, Mizuki SAKAMOTO, Hiroshi YAMADA, Tomohiro MORISAKI and LHD Experiment Group, Plasma Fusion Res. 10, 1202074 (2015).