  Helium bubbles can form in materials upon exposure to irradiation. It is well
known that the presence of helium bubbles can cause changes in the mechanical
behavior of materials. To improve the lifetime of nuclear components, it is
important to understand deformation mechanisms in helium-containing materials.
In this work, we investigate the interactions between edge dislocations and
helium bubbles in copper using molecular dynamics (MD) simulations. We focus on
the effect of helium bubble pressure (equivalently, the helium-to-vacancy
ratio) on the obstacle strength of helium bubbles and their interaction with
dislocations. Our simulations predict significant differences in the
interaction mechanisms as a function of helium bubble pressure. Specifically,
bubbles with high internal pressure are found to exhibit weaker obstacle
strength as compared to low-pressure bubbles of the same size due to the
formation of super-jogs in the dislocation. Activation energies and rate
constants extracted from the MD data confirm this transition in mechanism and
enable upscaling of these phenomena to high length-scale models.
