Computer simulations of the collision cascade process were used to investigate surface densification during ion beam assisted deposition (IBAD). The objective of the investigation was to see if densification resulted directly from the cascade, without any contribution from diffusion enhancement brought on by the bombardment. Calculations, using the computer code MARLOWE, were carried out for Ar bombardment of a crystalline Ge target, containing a void, using ion beam energies of 0.065, 0.5 and 1 keV. These results were used as data for a differential equation that describes the effect on void size of the simultaneous Ge atom deposition and Ar ion bombardment of a substrate containing voids. The present attempt examined the effects of irradiations on voids of 17 and 35 vacancies.