  Under low energy and high flux/fluence irradiation of helium (He) atoms, the
formation and bursting of He bubbles on tungsten (W) surfaces play important
roles in the morphological evolution of component surfaces and impurity
production in fusion reactors. Microscopically, the bursting of He bubbles is a
stochastic process, and He bubbles have statistically average lifetimes. In the
present paper, a molecular dynamics-based method was developed to extract, for
the first time, the lifetime of He bubbles near tungsten surfaces. It was found
that He bubble bursting can be treated as an activated event. Its occurrence
frequency or, equivalently, the average lifetime of bubbles follows the
Arrhenius equation. For a given bubble size, the activation energy exhibits a
good linear dependence with the depth, and the pre-exponential factor obeys the
Meyer-Nedle rule. These results are useful for establishing a model in
multi-scale simulations of impurity production in the fusion plasma and of the
morphological evolution of component surfaces.
