Modifications in divertor and scrape-off layer conditions with lithium coatings in NSTX

Two lithium evaporators were used in NSTX to deposit lithium coatings on graphite plasma-facing tiles in the lower divertor, enabling neutral deuterium pumping and resulting in reduced recycling. This was evident from the reduction by 50\% -- 80\% in D$_{\alpha}$ poloidal and divertor brightnesses, as well as the ion outfluxes, edge neutral pressure, core and divertor $n_e$. The two point and multi-fluid UEDGE code modeling suggested a shift of the outer divertor operating space toward the sheath-limited transport regime with lithium. Particle balance calculation showed that the deuteron inventory was well controlled and remained nearly constant in the long (1.2--1.4 s) ELM-free H-mode discharges with lithium coatings. However, $n_e$ rose due to the increasing carbon inventory. The carbon source, estimated from C~II and C~III intensities and atomic S/XB factors, was reduced, suggesting that impurity accumulation was due to the improved particle confinement. Supported by the U.S. DOE under Contracts DE-AC52- 07NA27344, DE-AC02-09CH11466, DE-AC05-00OR22725, DE-FG02-08ER54989, and W-7405-ENG-36.