Effect of surface quality on hydrogen/helium irradiation behavior in tungsten

Abstract

As the plasma facing material in the nuclear fusion reactor, tungsten has to bear the irradiation impact of high energy particles. The surface quality of tungsten may affect its irradiation resistance, and even affect the service life of fusion reactor. In this paper, tungsten samples with different surface quality were polished by mechanical processing, subsequently conducted by D2+ implantation and thermal desorption. D2+ implantation was performed at room temperature (RT) with the irradiation dose of 1 × 1021 D2+/m2 by 5 keV D2+ ions, and thermal desorption spectroscopy measurements were done from RT to 900 K. In addition, He irradiation was also performed by 50 eV He+ ions energy with the fluxes of 5.5 × 1021 m−2s−1 and 1.5 × 1022 m−2s−1, respectively. Results reveal that the hydrogen/helium irradiation behavior are both related to surface quality. Samples with high surface quality has superior D2+ retention behavior with less D2 retained after implantation. However, such samples are more likely to generate fuzzes on the surface after helium irradiation. Different morphologies (smooth, wavy, pyramids) after helium irradiation also demonstrates that the surface morphology is related to tungsten crystallographic orientation.