Electronic effects in radiation damage simulations

A methodology for including electronic effects in classical radiation damage simulations is presented. The method is used to calculate the number of residual defects for low energy (10 keV) cascades in Fe, as a function of the electron–phonon coupling strength. It was found that strong electron–phonon coupling reduced the number of residual defects by rapidly removing energy from the cascade and reducing the thermal spike. Intermediate coupling increased the number of defects by quenching the thermal spike and reducing defect recombination. Thermostatting the cascade with the local, time dependent electronic temperature, rather than the ambient temperature, reduced the number of residual defects by enhancing defect recombination. Swift heavy ion irradiation in tungsten was modeled using the same methodology. In this case we found that the number of residual defects created by a given electronic stopping power was strongly dependent on the temperature variation of the electronic heat capacity. In contrast to cascade simulations, the interstitials were located closer to the core of the ion track than the vacancies.