Properties of vacancy complexes with hydrogen and helium atoms in tungsten from first principles

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Abstract

Tungsten and its alloys are the primary candidate materials for plasma-facing components in fusion reactors. The material is exposed to high-energy neutrons and the high flux of helium and hydrogen atoms. In this work we have studied the properties of vacancy clusters and their interaction with H and He in W using density functional theory. Convergence of calculations with respect to modeling cell size was investigated. It is demonstrated that vacancy cluster formation energy converges with small cells with a size of 6 × 6 × 6 (432 lattice sites) enough to consider a microvoid of up to six vacancies with high accuracy. Most of the vacancy clusters containing fewer than six vacancies are unstable. Introducing He or H atoms increases their binding energy potentially making gas-filled bubbles stable. According to the results of the calculations, the H2 molecule is unstable in clusters containing six or fewer vacancies.

Original languageEnglish
Pages (from-to)52-59
Number of pages8
JournalFusion Science and Technology
Volume71
Issue number1
DOIs
StatePublished - Jan 2017

Funding

This research was sponsored by the U.S. Department of Energy (DOE), Office of Fusion Energy Sciences and Office of Advanced Scientific Computing Research through the Scientific Discovery through Advanced Computing (SciDAC) Project on Plasma-Surface Interactions under award DE-SC0008875, under contract with UT-Battelle, LLC, and by the DOE, Office of Fusion Energy Sciences, under contract DE-AC05-00OR22725 with UT-Battelle, LLC. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the DOE under contract DE-AC02-05CH11231.

Keywords

  • Binding energy
  • Hydrogen and helium in tungsten
  • Plasma-facing material

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