The energy of helium filled platelets and bubbles in molybdenum

Abstract

Theoretical models are developed to describe the observed behaviour of helium platelets in molybdenum, which grow and then collapse into clusters of bubbles. Firstly a fully dynamic simulation of helium in a two-dimensional structure is performed. Then simplified models of platelets and bubbles filled with helium are discussed, the calculated energies of which indicate that platelets should be higher in energy for 3 He/vacancy. A cluster of several bubbles is shown, under conditions of high internal pressure, to be of lower energy than a single large bubble due to the elastic interaction between bubbles on the assumption that this is approximately the same in magnitude as for the void lattice.