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Author(s):
T. Hino, T. Hirata, N. Ashikawa, S. Masusaki, Y. Yamauchi, Y. Nobuta, N. Ohyabu, A. Sagara, N. Noda, A. Komori, O. Motojima and LHD Experimental Group
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Title:
Hydrogen Concentration of Co-deposited Carbon Films Produced in the Vicinity of Local Island Divertor in Large Helical Device
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Date of publication:
Oct. 2008
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Key words:
21 IAEA Fusion Energy Conference, EX/P4-8
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Abstract:
It is quite important to evaluate hydrogen concentration of co-deposited carbon film/dust to estimate in-vessel tritium inventory in ITER. The co-deposited carbon films were prepared at the wall of pumping duct in Local Island Divertor experiments of LHD. The hydrogen concentration of the co-deposited carbon film at the wall not facing to the plasma with a low temperature was extremely high, 1.3 in the atomic ratio of H/C. This value is triple times higher than the previous value obtained by hydrogen ion irradiation to graphite. The crystal structure of the co-deposited carbon film observed by Raman spectroscopy showed very unique structure (polymeric a-C:H), which is well consistent with the high hydrogen concentration. The accumulation of in-vessel tritium inventory is also discussed.
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