Shock response of He bubble in single crystal tungsten: molecular dynamics simulation study

Nonequilibrium molecular dynamics simulations are performed to study the shock response of He bubble with various He-vacancy ratios in single crystal W. Simulation results show that the plastic deformation mode of He bubble is realized by emission of a [100] vacancy type of prismatic dislocation loop, which is formed by reaction of 1/2<111> type of edge dislocations. He bubble with high He-vacancy ratio is more stable than that with low He-vacancy ratio. Finally, the plastic deformation mode and stability of the He bubble are discussed in term of elasticity theory. It is found that the distribution character of resolved shear stresses on the bubble surface is the underlying cause to control the formation of the vacancy type prismatic dislocation loop; and that the resolved shear stress on the He bubble surface decreases with increase of He-vacancy ratio is the reason why He bubble can be stabilized by increase of its He-vacancy ratio.