Ion-driven deuterium retention in high-Z metals

The candidate armour material must provide high temperature resistance and accommodate the operation conditions with minimal erosion and acceptable tritium retention. Refractory metals such as tungsten and molybdenum can provide these capabilities and accommodate the high energy deposition. However, a major concern is the possible tritium and helium inventories from ion implantation. The deuterium retention in polycrystalline tungsten (W) and molybdenum (Mo) has been investigated for various irradiation temperatures, incident ion energies and fluences at Garching ion beam facility by means of thermal desorption spectroscopy. Lower deuterium retention in Mo compared to W was observed at moderated temperatures. Model including the deuterium implantation, diffusion, trapping and second order of desorption was used to understand deuterium inventory and release kinetics. The mechanism of the deuterium retention in W and Mo is discussed.