The formation of defect clusters in aluminium by ion bombardment

Pre-thinned foils of aluminium have been bombarded by 85 kev H+, He+, Ne+, A+, Kr+ and Xe+ ions. Electron microscope observations have shown that the formation of point defect clusters in these foils is dose rate dependent. In foils bombarded by H+ ions the number of observable point defects increased with increasing dose, whereas the total number of clusters and loops decreased. This is attributed to the mobility and interaction of loops during bombardment. The number of observable point defects was much greater after bombardment by Xe+, Kr+ and A+ ions than after the same dose of He+ or H+ ions. These observations are explained in terms of simple displacement theory.