D and He retention in thin Li films deposited on graphite substrates irradiated at high fluence*

Plasma Materials Interactions in tokamaks remain as a challenging area in the progress of fusion energy. The use of Li as Plasma Facing Component (PFC) has been explored in different machines, showing improvements in plasma performance. Laboratory and computational studies have observed lithium’s ability to retain D and H. Yet questions remain about the interplay between Li surfaces and plasmas. DIONISOS at the MIT–PSFC is an PFC analysis facility equipped with a high-flux plasma source attached to an ion accelerator to perform Ion Beam Analysis (IBA) during irradiations. Recently, a Li evaporator was installed in DIONISOS. Now DIONISOS provides the ideal scenario to investigate the properties of Li, and its interaction with oxygen and different plasmas. We have investigated the role of O in the retention of D and He by Li coatings deposited on graphite and metallic substrates. The O, D and He contents in the coatings were measured as a function of time and plasma fluence using IBA. The O% of the films increases with time following a logistic type trend. The data show increments in the O% with He irradiations up to 50%. The conclusion of this analysis provide tools to optimize the role of Li as conditioning technique.