Title: Non-dilute helium-related defect interactions in the near-surface region of plasma-exposed tungsten

Abstract

We report a systematic energetic analysis of helium-related defect interactions that mediate helium (He) segregation on surfaces of plasma-exposed tungsten at different levels of He ion implantation. We focus on high He fluences that increase the He content in the plasma-exposed material well beyond the dilute limit of He concentration and employ atomic configurations generated by large-scale molecular dynamics simulations of He-implanted tungsten. We perform systematic molecular statics computations of cluster–defect interaction energetics in the highly defect-rich near-surface region of plasma-exposed tungsten for small mobile helium clusters as a function of the clusters' distances from the surface. In this region, mobile clusters are also subjected to the stress fields generated by defects such as helium bubbles and other clusters, which govern cluster–defect interactions in addition to the cluster–surface interaction. Based on systematic investigation of individual cluster–defect interactions, we develop a mathematical framework to describe the interaction energy landscapes consisting of elastic interaction potential perturbations to finite-width square-well potentials, where the potential well accounts for cluster trapping by the defect at close range and subsequent coalescence and the perturbation potential is parameterized according to elastic inclusion theory. Superposition of all the relevant interaction potentials provides a comprehensive description of the interactionmore » energy landscape that would be experienced by a small mobile cluster along its migration path toward the plasma-exposed surface at high He fluences. Such descriptions are particularly important for developing atomistically informed, hierarchical multi-scale models of helium cluster dynamics in plasma-facing materials.« less

Authors:

Weerasinghe, Asanka  ^[1];

• Search DOE PAGES for author "Weerasinghe, Asanka"
• Search DOE PAGES for ORCID "0000-0001-7749-6823"

Hu, Lin ^[1]; Hammond, Karl D.  ^[2];

• Search DOE PAGES for author "Hammond, Karl D."
• Search DOE PAGES for ORCID "0000-0002-5424-8752"

Wirth, Brian D.  ^[3];

• Search DOE PAGES for author "Wirth, Brian D."
• Search DOE PAGES for ORCID "0000-0002-0395-0285"

Maroudas, Dimitrios  ^[1]

• Search DOE PAGES for author "Maroudas, Dimitrios"
• Search DOE PAGES for ORCID "0000-0001-9297-8839"

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+ Show Author Affiliations

1. Univ. of Massachusetts, Amherst, MA (United States)
2. Univ. of Missouri, Columbia, MO (United States)
3. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:

Thu Oct 29 00:00:00 EDT 2020

Research Org.:

Univ. of Massachusetts, Amherst, MA (United States); Univ. of Missouri, Columbia, MO (United States); Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR). Scientific Discovery through Advanced Computing (SciDAC); USDOE Office of Science (SC), Fusion Energy Sciences (FES)

OSTI Identifier:

1774786

Alternate Identifier(s):

OSTI ID: 1693455

Grant/Contract Number:  

SC0018421; 4000135920; 4000159698; AC02-05CH11231; AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Applied Physics

Additional Journal Information:

Journal Volume: 128; Journal Issue: 16; Journal ID: ISSN 0021-8979

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 77 NANOSCIENCE AND NANOTECHNOLOGY; plasma-facing materials; plasma-exposed tungsten; nanostructure formation; defect interaction; helium implantation; molecular-dynamics simulation