Clustering and dislocation loop punching induced by different noble gas bubbles in tungsten: a molecular dynamics study

Abstract

Different behaviours of noble gas X (X = He or Ne) atoms in the bulk and on the surface of tungsten (W) have been studied with molecular dynamics simulations to explore the fuzz formation induced by different noble gas bubbles. The formation of X clusters and bubbles in bulk W were simulated at temperatures from 400 to 2000 K. The results showed that higher temperature promotes the nucleation of X bubbles, and the sizes of self-interstitial atoms and X-vacancy clusters of Ne in W were larger than those of He in W at nano-scale, which indicates that Ne atoms can be trapped more easily than He atoms in W. The continuous nucleation processes of He/Ne bubbles near the surface of bulk W were also simulated. When the sizes of the X bubbles were large enough, the behaviour of dislocation loop punching was observed for both He and Ne clusters. From the comparison of the pressure of He/Ne bubble, it is found that the He-bubble can induce the loop-punching with lower critical pressure than the case of Ne-bubble. These results indicate a new understanding of noble gas effects in W in fusion reactors.