In situ observation of deuterium trapping in self-ion irradiated tungsten

Characteristics of irradiation-induced hydrogen trapping in tungsten were investigated by observing deuterium concentration profiles under continuous deuterium plasma exposure. Tungsten samples called A3 and A4 were 1.5-MeV W irradiated with an average of 0.63 and 4.2 dpa, respectively, and another sample called A5 was 5.0-MeV W irradiated with 54 dpa. Results show that traps were produced around 500 K, a recovery stage of interstitials, and were suggested to migrate from the damaged region to greater depths within the samples. The number of traps significantly increases with displacement at low dpa and then gradually increases around 0.1 dpa. Traps are effectively produced at high temperature irradiation. The trapping energy of 0.70 eV in A3 and A4 is the same as He- and H- irradiated samples. These traps are likely point-defect-like sites that accompany interstitial clusters such as dislocation loops.