Speaker
Mizuki Noguchi
(Advanced Energy Engineering Science)
Description
It is important to understand tritium (T) desorption behavior from plasma-facing materials of a fusion reactor in order to discuss tritium recovery method from in-vessel components. Tungsten (W) is a candidate material for plasma-facing components. Although a sputtering rate of W by hydrogen isotopes is low, a certain amount of W deposition layer will be formed on plasma-facing wall. In this work, T desorption behavior from W deposition layer exposed to gaseous T was investigated by imaging plate (IP) technique.
Samples of W deposition layer were formed on W substrates by hydrogen RF plasma sputtering. Prepared samples were separately put in a reaction tube and exposed to the T-D gaseous mixture (7.2% T/D) at 573 K or 773 K for 3 hours. Then, the closed reaction tube contained the samples was transported into a glove box filled with argon and T level of the samples were investigated by IP technique without air exposure. After that, annealing (368, 423, 573, 773 and 973 K) and following IP measurement were repeatedly performed. For comparison, the W substrates without W deposition layer were exposed to the T-D gas mixture at the same conditions.
The initial intensities of photo-stimulated luminescence (PSL) were 1029 PSL/mm22/h for the W deposition layer and 81 PSL/mm22/h for the W substrate. A part of retained T in W deposition layer was released at a low temperature of 368 K. However, the majority of the retained T was removed at 773 K for the sample exposed at 573 K and removed at 973 K for the sample exposed at 773 K. These results indicate that the formation of the W deposition layer increases the T inventory in the vessel and T removal from W deposition layer by in-vessel baking at around 423 K is limited.
Co-authors
Akira Taguchi
(Hydrogen Isotope Research Center, University of Toyama, 3190, Gofuku, Toyama-shi, Toyama, Japan)
Kazunari Katayama
(Advanced Energy Engineering Science, Kyushu University, 6-1, Kasugakoen, Kasuga-shi, Fokuoka, Japan)
Mizuki Noguchi
(Advanced Energy Engineering Science, Kyushu University, 6-1, Kasugakoen, Kasuga-shi, Fokuoka, Japan)
Naoko Ashikawa
(National Institute for Fusion Science, 322-6, Oroshi-cho, Tokishi, Gifu, Japan)
Satoshi Fukada
(Advanced Energy Engineering Science, Kyushu University, 6-1, Kasugakoen, Kasuga-shi, Fokuoka, Japan)
Yuji Torikai
(Hydrogen Isotope Research Center, University of Toyama, 3190, Gofuku, Toyama-shi, Toyama, Japan)
