Trapping and thermal diffusion for energetic deuterium implanted into SiC

During ITER and DEMO reactor operation Li-Pb blanket flow channel inserts made from SiC will be exposed to both radiation and tritium. Absorption, desorption, and tritium diffusion are expected to occur and will strongly depend on the irradiation conditions; temperature, and neutron and gamma fluxes. Reaction bonded (RB) SiC samples were deuterium implanted at both room temperature and 450 °C at different implantation energies and the corresponding TSD spectrum was obtained for each implantation energy. After implantation the samples were subjected to SIMS analysis. The TSD spectra obtained for all the samples implanted at different energies are very similar and characterized by a prominent deuterium desorption occurring at temperatures between 450 and 1000 °C with a maximum that exhibits a clear trend to shift toward higher temperature as either implantation energy or implantation temperature increase. SIMS analysis before heating the deuterium implanted samples indicates that the implanted deuterium has a tendency to become bonded to Si rather than to C. The SIMS analysis shows that once heated up to 1000 °C only part of the implanted deuterium was thermally released. The temperature shift observed when increasing the deuterium implantation energy and, hence, penetration, implies a deuterium diffusivity value at 700 °C of about 8.5 × 10−17 m2/s.