Trapping of deuterium in beryllium

The thermal release of deuterium (D) implanted into beryllium and the internal redistribution between traps at different depths was studied using ion-beam analysis methods. These methods allow surface effects and trapping to be characterized independently which is difficult from measurements of thermal release alone. At low concentrations D is trapped at lattice damage and is thermally detrapped around 450deg C. Transport simulations indicate that the energy barrier for detrapping is about 2.3 eV. At high concentrations D precipitates into gas bubbles. Release of D from the bubbles occurs by permeation from high pressure D2 gas inside the bubbles through the Be lattice to the surface. The permeability of D through Be determined from these experiments was about 2x105 D/(cm s atm1/2) at 600deg C, seven orders of magnitude smaller than the value calculated from published solubility and diffusivity data. The oxidized Be surface did not limit the D release. (orig.)