(551a) Model of Helium Bubble Density and Growth in Tungsten from Equations of State

Helium bubbles in plasma-facing tungsten are responsible for degradation of material properties and deformation of the surface at the length scale of 10–100 nm. Simulations have shown that helium bubbles that are relatively far from the tungsten surface consistently grow in a well-defined band of helium/vacancy ratios. The mean bubble density for a given bubble size is also well-defined. We previously suggested an empirical correlation for bubble density, namely n_He = 5 n_V^0.86, where n_He is the number of helium atoms in the bubble and n_V is the number of vacancies. Here, we explore the possibility of a theoretically-based correlation for bubble density based on material properties and plasma-related defect characteristics.