Comparative recycling analysis of discharges with varying lithium deposition on the Lithium Tokamak eXperiment-β*

The Lithium Tokamak eXperiment-β (LTX-β) has been studying the effect of complete coverage of its plasma facing components (PFCs) with lithium. The LTX-β vacuum vessel was recently vented after 5 years of continuous operation under vacuum. During these 5 years a number of operational and plasma diagnostics were implemented on the device to better understand and diagnose plasma discharges with low fuel recycling. A comparative analysis of these discharges with PFCs coated with partially passivated and clean lithium coatings is presented. A supersonic gas injector was used to diagnose effective particle confinement times, across a wide range of surface conditions. Multi-element poloidal and toroidal Lyman-α arrays were used to track neutral hydrogen inventory. Edge langmuir probes measured edge plasma density and temperatures. A 40 channel toroidal Soft X-ray array was used to monitor toroidal and poloidal mode activity. In general, effective particle confinement times are seen to reduce along with neutral density population, even when compared among shots with similar density and equilibria as more lithium is evaporatively deposited. A comparison of all these discharges for liquid lithium PFCs will also be presented along with estimates of DEGAS2 calculated global recycling coefficients and TRANSP calculated energy confinement times.