Studies of T$_{e}$, n$_{e}$, and Particle Flux at the Divertor Surface during NBI Heating and Various Divertor Configurations in H-mode Plasmas in NSTX

Interaction of the plasma with the divertor surfaces has been studied using an array of Langmuir probes and other divertor diagnostics in NSTX NBI heated H-mode plasmas[1]. These studies cover a range of plasma conditions including NBI injection power scans and different divertor configurations. Studies were done mainly with a toroidal field of B$_{t}$ = 0.45 Tesla, plasma current, I$_{p}$, in the range of 0.6 to 1.0 MA, and NBI power in the range 1\underline {$<$} P$_{b}$ \underline {$<$} 6MW. An array of Langmuir probes, flush mounted with the surfaces of the divertor tiles, was used to obtain divertor T$_{e}$, n$_{e}$ and particle flux. The particle flux to the probes increased with P$_{b}$, however, the variation in T$_{e}$ was more complex. Results were obtained for lower single null (LSN) and double null (DN) divertor configurations and these will be compared. Correlations between probe T$_{e}$, n$_{e}$, and particle flux, and divertor heat flux, D$_{\alpha }$ signals and other divertor diagnostics will also be discussed. [1] C. E. Bush, et al., Physics of Plasmas \textbf{10} (2003) 1755. *This work was supported by US DoE contract DE-AC05-00OR22725.