DEFECT PRODUCTION IN TUNGSTEN - A COMPARISON BETWEEN FIELD-ION MICROSCOPY AND MOLECULAR-DYNAMICS SIMULATIONS

Molecular dynamics (MD) computer simulations of 20 - 30 keV self-ion b ombardment of W were performed and compared to past field-ion microsco py (FIM) studies [M. I. Current et al., Philos. Mag. A 47, 407 (1983)] . The simulations show that the unusually high defect production effic iencies obtained by FIM are a consequence of a surface effect, which g reatly enhances defect production compared to that in the crystal inte rior. Comparison of clustering of vacancies and the formation of inter stitial atoms found in the FIM experiments and MD simulations shows ov erall good agreement.