PSI modeling of liquid lithium divertors for the NSTX tokamak

We analyzed plasma surface interaction issues for the planned Module-A static liquid lithium divertor for NSTX using coupled codes/models describing the plasma edge, divertor temperature, and erosion/redeposition, with input data from tokamak and laboratory experiments. A 300 nm lithium pre-shot deposited coating will strongly pump impinging D+ ions. This yields a low-recycle SOL plasma with high plasma temperature, T-e similar to 200-400 eV, low density, N-e similar to 1-3 x 10(18) m(-3), and peak heat loads of similar to 8-20 MW/m(2), for 2-4 MW core plasma heating power. This regime has advantages for the NSTX physics mission. Peak surface temperature can be held to an acceptable <= 470 degrees C with moderate strike point sweeping (10 cm/s) using a carbon (for 2 MW) or Mo/Cu or W/Cu substrate (2-4 MW). Erosion/redeposition analysis shows acceptable coating lifetime for a 2 s pulse and low core plasma contamination by sputtered lithium. (c) 2004 Elsevier B.V. All rights reserved.