Hydrogen isotope behavior and its interaction with post irradiated energetic helium in SiC

The D-2(+) was irradiated into SiC up to the saturation and thereafter He+ irradiation was performed to elucidate interaction mechanism between hydrogen isotope retained in SiC and irradiated energetic He+ by means of X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). It was found that D was trapped by both of Si and C by D-2(+) irradiation and only D bound to Si interacted with irradiated He+ in the initial He+ irradiation stage. Some damaged structures were introduced into SiC by both of D-2(+) and He+ irradiation. By heating after the irradiation experiments, most of SiC structure was recovered at the temperature above 1000 K. However, some free C was migrated toward the surface and aggregated on the surface of SiC. This fact indicates that the C impurity would contaminate the plasma and/or the tritium breeding materials, which is thought to be contacted with the SiC inserts.