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


Hydrogen Concentration of Co-deposited Carbon Films Produced in the Vicinity of Local Island Divertor in Large Helical Device

Date of publication:

Oct. 2008

Key words:

21 IAEA Fusion Energy Conference, EX/P4-8


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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