The influence of radiation damage on the plasma-induced deuterium retention in self-implanted tungsten

The prediction of hydrogen isotope retention in n-irradiated tungsten (W) is an important topic for edge plasma research as it has significant implications for the operation of ITER and fusion reactors. Direct measurement of tritium retention in n-irradiated tungsten is a difficult task. The self-implantation of W is the most promising approach because it generates dense cascade with large clusters which are typical for n-irradiation and any chemical effects are avoided. Pre-damaged samples were exposed to pure and He-seeded deuterium plasmas on both front (undamaged) and rear (damaged) sides in order to separate deuterium (D) retention in plasma-induced traps and in displacement damage created by fast tungsten ions. Irradiation was done up to a damage level expected from the end-of-life neutron fluence in ITER. The diffusion model with dynamic trap formation during irradiation was validated by comparison with experiments and applied for calculation of hydrogen isotope retention in ITER in the presence of neutron irradiation.