Using Accelerated Molecular Dynamics Simulations to Understand Helium Bubble Evolution in Tungsten*

Designing materials to withstand the extreme conditions of fusion requires understanding, at the atomic scale, material evolution at those same conditions. Accelerated molecular dynamics (AMD) methods, which extend the timescale of conventional molecular dynamics while retaining the fidelity of the interatomic interactions, is a key tool in developing this understanding. We have used these methods to examine the behavior of helium bubbles in tungsten with the goal of informing higher level models of basic mechanisms over timescales relevant for fusion conditions. This talk will summarize both past results as well as more recent work, highlighting and contrasting the growth mode of bubbles in bulk tungsten versus at a grain boundary, examining the effect of helium arrival rate on the development and evolution of bubble networks, and determining the rate of migration of embryonic bubbles. Together, these results complement other simulation studies and provide a more comprehensive picture of the dynamics associated with helium bubbles in tungsten.