Post exposure time dependence of deuterium retention in lithium and lithium compounds

Abstract

Lithium (Li) coating of plasma-facing components (PFC) has led to improved plasma performance in fusion experiments due to the effectiveness of Li in retaining hydrogen (H) isotopes and thus reducing recycling. Since Li readily reacts with background gases present in fusion experiments, it is important to understand and parameterize the time dependence of deuterium (D) retention in Li and Li compounds for applications of Li under future long-pulse plasma conditions. D retention in pure Li and composite LiO and LiCO films was studied as a function of time after these films were exposed to 450 eV D2+ ion irradiation. The amount of deuterium retained in both Li and LiO films at 300 K decreased at the same rate by 45% after 16 h. The amount of D retained in LiCO films was found to be independent of time up to 3 days. Increasing the temperature of a pure Li film to 420 K increased this rate of decrease by 50%, while increasing the thickness of the lithium film from 3 to 16 monolayers had no effect on the decrease rate. Keywords: Deuterium retention, Lithium, Lithium compounds, Time dependence