In situ electron microscope observations of defects showed that incident high-energy electrons influenced the evolution of the microstructure of an irradiated material; reducing the number of defects via microscopy. The origin of this phenomenon was investigated by using W as a case study. It was found that the displacement of atoms due to electron impacts gave rise to stochastic jumps of a defect over several interatomic distances. However, the frequency of these events under normal conditions was too low to influence the high thermal mobility of defects in a pure material. At the same time, the analysis showed that the migration of defects driven by electron impacts provided the predominant mechanism of diffusion in a material where the defects were pinned by solute atoms or impurities.

Driven Mobility of Self-Interstitial Defects under Electron Irradiation. S.L.Dudarev, P.M.Derlet, C.H.Woo: Nuclear Instruments and Methods in Physics Research B, 2007, 256[1], 253-9