Deuterium retention in VPS-W coated vanadium alloy (V–4Cr–4Ti)

Abstract D retention in a VPS W coated V alloy (V–4Cr–4Ti, NIFS Heat 2) was investigated by an ion beam irradiation with a HiFIT device. Irradiation temperature changed from 473 K to 773 K and ion fluence was 1024 m−2. In addition, during ion irradiation atmospheric pressure was 0.5 mTorr. It was found that ambient gas absorption was the dominant process for D retention. Ion irradiation could enhance gas absorption probably due to surface modification (oxide layer removal) and could produce ion induced trapping sites. Although these ion induced processes can be avoided by W coating layers, D retention is still significant for VPS-W coated V alloy. D trapping could be done mainly in V-alloy and its mechanisms could be related to some intrinsic defects in V alloy and formation of titanium hydride at elevated temperature.