Deuterium retention and release from highly irradiated annealed tungsten after exposure to a deuterium DC glow discharge

Abstract

Samples from tungsten rods irradiated by 800 MeV protons in the Los Alamos Neutron Science Center have been used in experiments to study the effects of radiation damage and annealing on the retention of hydrogen isotopes. These samples were annealed and then exposed to deuterium ions using a DC glow discharge. Following exposure, the samples were subjected to a linear temperature ramp from ∼300 to ∼1500 K, and the offgas analyzed by mass spectrometry. The results indicate that annealing to a temperature of only 1273 K for 6 h effectively removed all irradiation-produced traps, and that hydrogen trapping at voids is not as prevalent as had been assumed. Modeling the deuterium release suggests that most of the trapping occurred in near-surface 1.4 eV traps, in a low concentration of uniform 1.4 eV traps, and in 0.95 eV traps likely resulting from oxygen diffusion from the original water-cooled irradiation environment.