TEM investigation of the influence of dose rate on radiation damage and deuterium retention in tungsten

Tungsten targets were first irradiated with high energy W6+ ions (20 MeV) with different dose rates at 800 K and then loaded with deuterium at room temperature to decorate the displacement damage created in the first step. Detailed microstructure investigations were performed and compared with calculated damage profiles and deuterium depth profiles to link defect characteristics with the ability to retain hydrogen isotopes. Results directly indicate that depending on the used dose rate dislocation density and characteristics change. However, deuterium retention does not. Thus, we conclude that overall dislocation density does not affect deuterium retention significantly. Changes in D retention were observed as function of the depth of the damaged zone. Variations of dislocation density were also depth dependent. Consequently, we link changes in D retention with the dislocation presence, number of implanted tungsten ions and other point defects. The latter seem to affects D retention the most.