The effect of W surface fuzz induced by He plasma on deuterium permeation

Abstract The permeation and retention of hydrogen isotopes in nuclear materials is critical to issues such as hydrogen embrittlement, tritium self-sufficiency, and radioactive safety in fusion reactors. Tungsten, the primary candidate for plasma-facing materials, undergoes high-flux helium plasma irradiation in fusion devices that may alter hydrogen isotope behaviors. However, few works have focused on the effects of helium plasma–induced surface modification on hydrogen permeation. This study investigates the effects of helium-induced surface fuzz structure on deuterium permeation through tungsten. Our findings indicate that the surface fuzz structure can significantly enhance deuterium permeation through tungsten, with the degree of enhancement positively correlated to both the thickness of the fuzz structure and the permeation temperature. In addition, as the temperature decreases, the contribution of the tungsten oxide layer covering the nanotendrils that hinder deuterium diffusion gradually becomes stronger, resulting in the weakening of the overall permeation enhancement. The influence of the fuzz characteristics on deuterium transport properties is discussed. This work implies that helium plasma–induced surface modification can considerably the deuterium transport behaviors in tungsten.