Evaluation of hydrogen retention behavior in tungsten exposed to hydrogen plasma in QUEST

Ayaka Koike, Moeko Nakata, Shota Yamazaki, Takuro Wada, Fei Sun, Mingzhong Zhao, Naoaki Yoshida, Kazuaki Hanada, Yasuhisa Oya

研究成果: Contribution to journalArticle査読

1 被引用数 (Scopus)

抄録

The W (tungsten) samples were placed at Top, Equator and Bottom plasma facing walls of QUEST (Q-shu University Experiment with Steady-State-Spherical Tokamak) device and exposed to 754 shots of hydrogen plasma during 2017A/W (Autumn/Winter) campaign. Thereafter, their surface morphologies and chemical states were evaluated by TEM (Transmission Electron Microscope) and XPS (X-ray photoelectron spectroscopy). The XPS results showed that a thick carbon layer about 3–18 nm has formed throughout the wall surface. Among them, the Bottom wall had the deposition layer with the thickness of 2 nm, which was thinner than the top wall, namely erosion-dominated. On the other hand, a thick C layer about 18 nm was deposited on the Equator wall. The additional 1 keV D2+ was implanted into these samples and the D (deuterium) retention enhancement was estimated. The D2 TDS (Thermal Desorption Spectroscopy) spectra for all the samples had two major desorption stages at 400 K and 650 K, namely the desorption of D trapped by irradiation damages and deposition layer. The erosion/deposition profile would be caused by wall position and plasma condition, like a current start-up experiment. The desorption temperature of H2 (hydrogen) was shifted toward higher temperature side compared to that exposed to previous plasma campaign (2016 A/W), suggesting that H was mainly accumulated in the deposition layer with forming C–H bonds.

本文言語英語
論文番号100856
ジャーナルNuclear Materials and Energy
26
DOI
出版ステータス出版済み - 3 2021

All Science Journal Classification (ASJC) codes

  • 核物理学および高エネルギー物理学
  • 材料科学(その他)
  • 原子力エネルギーおよび原子力工学

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