Plasma and Fusion Research
Volume 12, 1302048 (2017)
Letters
- Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan
- 1)
- National Institute for Fusion Science, Oroshi-cho, Toki 509-5292, Japan
Abstract
An additional deuterium irradiation was performed for long-term samples mounted on the first wall in the large helical device (LHD) to investigate the effect of mild baking (at 368 K) on fuel hydrogen removal from the modified surface. The efficiency of baking strongly depended on the surface conditions. In the erosion dominant area, almost all the retained deuterium was removed by baking, whereas only 17% and 13% of the retained deuterium were removed from the boron and carbon deposition areas, respectively. The results suggest that the erosion dominant area in the first wall can act as a pumping wall during the main discharge, and, in contrast, the fuel hydrogen retention can continuously increase in boron and carbon deposition areas owing to the low removal efficiency of fuel hydrogen given that the deposition continues during the plasma discharge.
Keywords
baking, desorption, retention, surface modification, deposition, deuterium irradiation
Full Text
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