Effect of temperature on microstructures and retention properties in tungsten exposed to D + He + Be mixture plasmas in PISCES

Abstract The influence of temperature on microstructures and D retention properties in tungsten exposed to D + He + Be mixture plasmas is investigated. For the low temperature exposure case at 573 K, the Be seeding to D + He mixture plasmas results in the suppression of high density He nano-bubbles, which are distinctive internal defects observed in He irradiated/exposed metals. In contrast, fine and high-density He bubbles appear for W exposed to D + He + Be mixture plasmas at higher temperatures of >773 K. TDS measurements also show that the influence of Be seeding to D + He mixture plasmas, which counteracts the significant reduction in D retention, becomes weak with increasing temperature. From XPS analyses, it is considered that Be 2 W is formed by interdiffusion and solid-state-reaction at the high temperature exposure case, and the influence of the metallic Be on surface properties gradually disappears with increasing temperature.