Preliminary Results from Hydrogen Adsorption, Concentration Measurement, and Distillation Experiments in Molten Lithium

Liquid lithium as a plasma-facing component (PFC) is attractive due to improved plasma performance and avoidance of erosion/redopsition and transient melting that plague traditional solid PFCs. Lithium PFCs are low-Z, have a high gettering potential, and allow access to a low-recycling regime. However, lithium uptake of hydrogenic species can be problematic for future fusion plants with limited tritium inventory. To address this issue, the University of Illinois is developing APOLLO, a flowing lithium loop containing a free-surface PFC in a magnetic field, capable of either deuterium plasma or electron beam heating, and a distillation column for the extraction of hydrogenic species. The distillation column will also have capabilities for hydrogen adsorption and concentration measurement experiments and is currently being designed. Within the distillation column, lithium will be heated to 700℃ by an induction heater and have the capability for exposure to a well-characterized hydrogen plasma. Hydrogen concentration will be measured with a resistance-based technique. For distillation experiments, the lithium will be heated to 700℃ and a resistively heated condensation stage will be positioned to allow for the collection of clean lithium to be recirculated into the loop. Preliminary results from commissioning this new chamber, prior to incorporation into the lithium loop, will be presented.