Formation of interstitial loops in tungsten under He ion irradiation was evaluated by microstructural observation and numerical model calculation. In the model, 2 types of mechanisms of interstitial loop nucleation were employed in addition to introducing an effect of trap mutation. When the binding energy of a self-interstitial atom to a He-vacancy complex was around 0.7eV, the irradiation-time dependence of calculated interstitial loop density showed good agreement with the experiment. The energy value (0.7eV) was consistent with molecular dynamics evaluations in the literature.

Formation of Interstitial Loops in Tungsten under Helium Ion Irradiation - Rate Theory Modeling and Experiment. Y.Watanabe, H.Iwakiri, N.Yoshida, K.Morishita, A.Kohyama: Nuclear Instruments and Methods in Physics Research B, 2007, 255[1], 32-6