HELIUM EFFECTS ON DISPLACEMENT CASCADE IN TUNGSTEN
Molecular dynamics (MD) simulations were performed to investigate He effects on displacement cascades in W. Helium content, proportion of interstitial and substitutional He and temperature were varied to reveal the various effects. The effect of interstitial He on the number of self-interstitial atoms (SIAs) produced during cascade damage appears to be insignificant. However, interstitial He tends to fill a vacancy (V). Nevertheless, this process is less favorable than SIA-V recombination particularly when excess SIAs are present before a cascade. The efficiency of He filling and SIA-V recombination increases as temperature increases due to increased point defect mobility. Likewise, substitutional He is more susceptible to displacement during a collision cascade than W. This susceptibility increases towards higher temperatures. Consequently, the number of surviving V is governed by the interplay between displaced substitutional He and SIA-V recombination. The temperature dependence of these processes results in a minimum number of V reached at an intermediate temperature.
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- Related Information: Fusion Materials Semiannual Progress Report for the Period Ending June 30, 2013, 54; DOE-ER-0313/54:223-227
- Oak Ridge National Laboratory, Oak Ridge , TN, United States(US).
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- Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
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- United States
- tungsten; radiation; damage; helium; fusion