Deuterium trapping and release in titanium-based coatings for TFTR

We have measured the deuterium trapping and thermal release characteristics of three candidate armor and limiter materials for TFTR: Ti explosively bonded onto Cu; TiB2 and TiC chemically vapor deposited on C. The re-emission rate of deuterium was monitored during bombardment with 10 keV D+3 and the post-implantation retention was measured with D(3He,α)H nuclear reaction profiling and linear ramp thermal desorption. Titanium claddings showed no thermal release of deuterium for fluences of 1019 D/cm2 at 375 K; at 775 K, only 65% of the fluence was released during implantation to 1018 D/cm2. This high retention is shown to result from titanium deuteride precipitation and the formation of a bulk deuterium solid solution. In contrast, the TiB2 and TiC coatings showed a rapid saturation in deuterium retention of approx. <= 1017 D/cm2. (orig.)