Effects of Helium Seeding on Deuterium Retention in Neutron-Irradiated Tungsten
Neutron-irradiated tungsten (W) samples were exposed to helium (He)–seeded deuterium (D) plasmas using a linear plasma device called Tritium Plasma Experiment in order to investigate the synergetic effects of neutron and He irradiations on D retention in W. Exposure to nonseeded D plasma was also performed for neutron-irradiated and nonirradiated W samples for comparison. Deuterium retention in neutron-irradiated W after D plasma exposure was two to three times larger than that in W without neutron irradiation. Nevertheless, He seeding in D plasma resulted in a drastic reduction in D retention. The cross-sectional observation by transmission microscopy showed formation of He bubble layers with a thickness of 10 to 20 nm. There is a possibility that alpha particles in fusion plasma reduce tritium retention in neutron-irradiated plasma-facing components with W layers.
Nobuta, Yuji; Shimada, Masashi; Taylor, Chase N.; Oya, Yasuhisa; Hatano, Yuji; Wu, Yaqiao; and Dubey, Megha. (2021). "Effects of Helium Seeding on Deuterium Retention in Neutron-Irradiated Tungsten". Fusion Science and Technology, 77(1), 76-79. https://doi.org/10.1080/15361055.2020.1843314