A diffusion approach to modelling of irradiation-induced cascades

Two of the most important factors crucial to irradiation damage correlation are the effects of damage rate and recoil spectrum. Both of these factors are intimately related to the details of spatial distribution of point defects and interstitial clustering in the cascade zone. In this paper, we report some preliminary results of an attempt to develop a diffusion-based methodology to study the evolution of the point defects during the cascade process. The present methodology utilizes a newly developed semi-numerical Green function scheme. It is shown that this continuum approach is computationally feasible. Two interesting and potentially important results from the present calculations are: (a) significant portions of the interstitials may be immobilized in the cascade zone by clustering and (b) a significant portion of the interstitials escaping the cascade zone may be di-interstitials which may have different diffusion properties from those of the mono-interstitials.