Multiscale modeling of radiation damage: applications to damage productionby GeV proton irradiation of Cu and W, and pulsed irradiation effects in Cu and Fe

The damage accumulation in Cu and W is investigated using a multiscale mode ling approach. The efficiency for defect production of displacement cascade s is calculated using molecular dynamics (MD). The simulation uses the reco il spectra from spallation reactions of 1.1 and 1.9 GeV protons as calculat ed with the Los Alamos High Energy Transport (LAHET) nuclear transport code . The total number of defects produced under these irradiation conditions i s obtained both from the NRT and MID approximations. The value for the chan ge in electrical resistivity produced by the irradiation-induced defect mic rostructure is compared to experimental values obtained from irradiations w ith protons of the above energies, showing a better agreement for the lower irradiation energy. The damage evolution is simulated with kinetic Monte C arlo, where the inputs for the calculation are the results from MID previou sly obtained. A large recovery of the damage is found at room temperature a s a result of the migration of interstitial clusters, single vacancies and small vacancy clusters to sinks such as dislocations. Finally the effects o f pulsed irradiation have been analyzed in Cu. and Fe with similar simulati on tools. The results indicate a clear influence of pulsing at I Hz, but no t at higher frequencies. (C) 2001 Elsevier Science B.V. All rights reserved .