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Title: Interactions of mobile helium clusters with surfaces and grain boundaries of plasma-exposed tungsten

We report results of atomistic computations for the interactions of small mobile helium clusters (He{sub n}) with free surfaces and grain boundaries (GBs) in tungsten toward development of continuum drift-diffusion-reaction models for the dynamics of mobile helium clusters in plasma-exposed tungsten. Molecular-statics (MS) simulations based on reliable many-body interatomic potentials are carried out for He{sub n} (1 ≤ n ≤ 7) clusters near sinks to obtain the potential energy profiles of the He{sub n} clusters as a function of the clusters' center-of-mass distance from a sink. Sinks investigated include surfaces, GBs, and regions in the vicinity of junctions where GBs intersect free surfaces. Elastic interaction potentials based on elastic inclusion theory provide an excellent description of the MS results for the cluster-sink interactions. The key parameter in the elastic models is the sink segregation strength, which is found to increase with increasing cluster size. Such cluster-sink interactions are responsible for the migration of small helium clusters by drift and for helium segregation on surfaces and grain boundaries in tungsten. Such helium segregation on sinks is observed in large-scale molecular-dynamics simulations of helium aggregation in model polycrystalline tungsten at 933 K upon helium implantation.
Authors:
;  [1] ; ;  [2]
  1. Department of Chemical Engineering, University of Massachusetts, Amherst, Massachusetts 01003-9303 (United States)
  2. Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States)
Publication Date:
OSTI Identifier:
22273439
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 17; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AGGLOMERATION; ATOMIC CLUSTERS; COMPUTERIZED SIMULATION; DIFFUSION; GRAIN BOUNDARIES; HELIUM; HETEROJUNCTIONS; MANY-BODY PROBLEM; MOLECULAR DYNAMICS METHOD; POLYCRYSTALS; POTENTIAL ENERGY; POTENTIALS; SEGREGATION; SURFACES; TUNGSTEN