The effect of ion damage on deuterium trapping in tungsten

A systematic study investigating the effect of ion-induced damage, due to prior ion implantation, on deuterium retention in tungsten has been performed. Implantations with 1.5 keV D 3 + ions (500 eV/D +) to 10 23 D/m 2 at 500 K show a factor of 3–4 increase in retention for specimens previously exposed to a fluence of 10 24 D/m 2 and a factor of 6–7 increase for specimens previously exposed to a fluence of 3 × 10 24 D/m 2 over specimens exposed only to an incident fluence of 10 23 D/m 2. However, implantations with 1.5 keV D 3 + (500 eV/D +) ions to 10 23 D/m 2 at 500 K on specimens previously exposed to a fluence of 10 25 D/m 2 show no increase in retention. Implantations with 3 keV D 3 + ions (1 keV/D +) at the above conditions give retention results which do not depend on prior implantation treatments; only a slight increase in retention values with cumulative fluence is observed. Possible mechanisms are suggested to explain the observed effects.