Deuterium retention and outgassing in Li-D co-deposits studies in Magnum-PSI

The influence of temperature on D retention in LiD co-deposits and outgassing was studied in Magnum-PSI. Additively manufactured W CPSs filled with Li were exposed to D plasmas. Polished and non-polished stainless steel witness plates (WPs) were placed on a heater adjacent to the CPSs, where Li and D co-deposited. The temperature of the WPs during plasma exposure was varied using a combination of plasma heating and the heater. The temperatures tested were between 170°C and 500°C. It was found that D retention in the co-deposits does not show any dependence on temperature up to 420°C, with the D concentration reaching ~ 42% atm. However, at 500°C, a thin film of Li was measured with no D retention. After plasma exposure, D outgassing studies were conducted at different temperatures (200-500)°C. It was observed that D outgassing occurred even at 200°C. The rate of outgassing increased with temperature. In addition to the effect of temperature on outgassing, the influence of D background pressure was investigated. D gas was injected into the vacuum chamber, resulting in a higher background D pressure than the LiD decomposition pressure. It was found that at 450°C and 400°C with P_D=15 Pa, P_D>P_decomLiD , the outgassing rate was slower compared to outgassing at 400°C in vacuum.