Helium diffusion and bubble evolution in tungsten nanotendrils

MA Cusentino and BD Wirth, COMPUTATIONAL MATERIALS SCIENCE, 183, 109875 (2020).

DOI: 10.1016/j.commatsci.2020.109875

We describe molecular dynamics simulations of helium implantation in geometries resembling tungsten nanotendrils observed in helium plasma exposure experiments. Helium atoms self-cluster and nucleate bubbles within the tendrillike geometries. However, helium retention in these geometries is lower than planar surfaces due to higher surface area to volume ratio which allows for continual bubble expansion and non- destructive release of helium atoms from the nanotendril. Limited diffusion of helium atoms deeper into the tendril was observed, and diffusion was enhanced with pre-existing, subsurface helium bubbles. Diffusion coefficients on the order of 10(-12)-10(-11)m(2)s(-1) were calculated. This suggests that while helium diffusion is low, it is still feasible that helium can diffuse to the base of a nanotendril to continue to drive fuzz growth.

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