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Author(s):
N. Yoshida, Y. Ohtawa, A. Ebihara, T. Akiyama, M. Tokitani, N. Ashikawa, K. Kawahata
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Title:
Reflectivity Reduction of Retro-Reflector Installed in LHD due to Plasma Surface Interaction
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Date of publication:
Oct. 2008
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Key words:
21 IAEA Fusion Energy Conference, FT/2-1
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Abstract:
Optical reflectivity of the retro-reflector installed in LHD as the first mirror was reduced seriously by plasma wall interaction. In order to understand the mechanism of the reflectivity reduction, optical and material properties of the mirror surfaces have been examined extensively. It was found that the deposited impurity layers caused the serious reduction of the reflectivity. Formation of iron oxide, bulges structure and He bubbles are the major factors for the reflectivity reduction in the wide wave length range.
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