Formation of interstitial loops in tungsten under helium ion irradiation: Rate theory modeling and experiment

Formation of interstitial loops in tungsten under helium ion irradiation has been evaluated by microstructural observation and numerical model calculation. In the model, two types of mechanisms of interstitial loop nucleation are employed in addition to introducing an effect of trap mutation. When the binding energy of an SIA to a helium-vacancy complex is around 0.7 eV, the irradiation-time dependence of calculated interstitial loop density shows good agreement with the experiment. The energy value (0.7 eV) is consistent with molecular dynamics evaluations in the literature.