Rate theory cluster dynamics simulations including spatial correlations within displacement cascades

Mean-field cluster dynamics (CD) using rate theory is a convenient method to simulate the nucleation, growth, and coarsening of clusters under continuous irradiation or ion implantation up to high doses. When displacement cascades are produced, clusters are directly nucleated in cascades, so that creation rates of clusters must be introduced in CD. However, these rates are difficult to determine since CD cannot intrinsically account for spatial correlations between clusters in cascades. In this article a space homogenization method is proposed to determine an effective irradiation source term for CD, based on the knowledge of the primary damage and on a modified kinetic Monte Carlo algorithm. The effective irradiation term is shown to be dynamic, in the sense that it depends on the cluster density in CD simulations. The interest of the method is demonstrated in iron in the case of 20-keV primary knock-on atoms and 60-keV helium implantation.