Deuterium retention in tungsten from exposure to plasma

Abstract

Experiments are described which characterize retention of deuterium in tungsten resulting from exposure to plasma at fluences up to 1022 D atoms cm−2. The influence of displacement damage on deuterium retention is investigated for damage levels up to 0.6 displacements per atom (dpa) produced by 12 MeV silicon ion irradiation. Near-surface retention associated with precipitation and blistering was seen in both damaged and undamaged material. Trapping at displacement damage was also observed. These experiments determined the number of traps produced versus dpa, and the rate at which they are filled during exposure to plasma. These results indicate that the increase in tritium inventory in the ITER divertor due to trapping at neutron damage should be relatively small due to the shallow depth of penetration of tritium to traps at lower temperatures (<200 °C) and the annealing of displacement damage at higher temperatures (>500 °C).