Atomic simulation of helium trapping in displacement cascades

A molecular dynamics method is applied to simulate displacement cascades in He-doped alpha-Fe and predominant analytical attention is paid to the clustering of He-participating defect clusters to reveal the trapping behaviors of helium atoms in radiation processes. It is found that the radiation temperature, PKA energy and helium concentration play complex roles in defect production. An increase in helium atoms increases the number of defects and the increasing rate is greatly enhanced with the increase in PKA energy and initial radiation temperature. Cascade collisions significantly promote helium trapping through two types of mechanism, thermally activated self-trapping and cascade defect-created capture. Thermally activated self-trapping rather than cascade defect capturing causes helium trapping in displacement cascades.