Dynamics of Hydrogen Isotope Absorption and Emission of Neutron-Irradiated Tungsten

Takeshi Toyama, Miyuki Yajima, Noriyasu Ohno, Tatsuya Kuwabara, Vladimir Kh Alimov, Yuji Hatano

Research output: Contribution to journalArticlepeer-review

Abstract

This overview presents recent results regarding hydrogen isotope absorption and emission dynamics in neutron-irradiated tungsten (W) using our recently developed Compact Diverter Plasma Simulator (CDPS), a linear plasma device in a radiation-controlled area. Neutron irradiation to 0.016 - 0.06 displacement per atom resulted in a significant increase in deuterium (D) retention due to trapping effects of radiation-induced defects. We analyzed the dependency of D retention on the D plasma fluence by exposing neutron-irradiated pure W to D plasma at 563K over a range of D fluence values. The total retention was revealed to be proportional to the square root of D fluence, indicating that the implanted D atoms first occupy the defects caused by neutron-irradiation near the surface and then the defects located in deeper regions. We further investigated the effects of post-plasma annealing on D emission; neutron-irradiated pure W was exposed to D plasma at 573K and was then annealed at the same temperature for 30 hours. Approximately 10% of the absorbed D was released by annealing, suggesting that a heat treatment of the plasma-facing component of a fusion reactor at moderately elevated temperatures could contribute to the removal of accumulated hydrogen isotopes. The experimental results obtained in this study were only available by investigating neutron-irradiated specimens with the CDPS system, which will be essential for future studies of material behavior and plasma-wall interactions in the fusion reactor environment.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalPlasma and Fusion Research
Volume15
DOIs
Publication statusPublished - 2020

Keywords

  • deuterium
  • neutron irradiation
  • TDS
  • tungsten

ASJC Scopus subject areas

  • Condensed Matter Physics

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