Effect of lithium on the power exhaust channel in NST

NSTX has been shown [1] to have peak heat fluxes up to 15 MW/m$^2$ where the heat flux width, when magnetically mapped to the midplane, decreases strongly with Ip (lambda$_q^{mid}~$I$_P^{-1.6}$) during high performance (I$_p$ = 1.2 MA, P$_{NBI}$ = 6 MW, $\delta$~0.7) H-mode discharges with boronization. However, with lithium wall conditioning, the effect on NSTX discharges has been to improve energy confinement [2], reduce ohmic flux consumption therefore extending the discharge lifetime, and the elimination of Edge Localized Modes (ELMs) when sufficient lithium is applied [3]. However, with significant lithium wall deposition, lambda$_q^{mid}$ contracts by 50-60\% and the dependence on I$_P$ is reduced (lambda$_q^{mid}~$I$_P^{- 0.4}$). A similar trend is observed in the profile width of divertor D$_\alpha$ profiles with significant lithium deposition. Measurements from flush mounted divertor Langmuir probes show a slight increase in electron density but electron temperature, T$_e$ is unchanged at $\sim$20eV. The scaling of the heat flux width will be reported as a function of pedestal parameters under lithiated conditions.