Deuterium retention and positron annihilation spectroscopy of self- irradiated tungsten

Self-ion irradiation of pure tungsten with 2 MeV W ions is used for simulating microstructures created by neutron irradiation in a fusion reactor. Electron microscopy was then applied to characterizing the defects formed in the samples as a result of ion irradiation. Some of the irradiated samples were then implanted with deuterium. Thermal Desorption Spectrometry (TDS) was performed to estimate the deuterium inventory as a function of irradiation damage. Application of Positron Annihilation Spectroscopy (PAS) to self-irradiated but not deuterium implanted samples enabled assessing the density of irradiation defects as a function of the exposure to high-energy ions. The PAS results show that the density of defects saturates at doses in the interval from 0.085 and 0.425 displacements per atom (dpa). These results are discussed in the context of recent theoretical simulations exhibiting the saturation of defect microstructure in the high irradiation exposure limit. Corresponding author. Email: Anthony.Hollingsworth@ukaea.uk