C$^{+6}$ impurity profiles in MST plasmas*

Temporally-resolved radial profiles of Doppler broadened C$^{+6}$ emission (343.4 nm) have been measured on the MST reversed-field pinch using Charge-Exchange Recombination Spectroscopy. Experimental observations indicate a hollow C$^{+6}$ density profile for both standard and improved confinement plasmas, throughout the duration of the diagnostic neutral beam pulse, even though the C$^{+6}$ ion temperature profile peaks at the center. Measurements are made on deuterium plasmas with density $\sim 1\times 10^{19} ~ m^{-3}$ and plasma current $\sim$ 400 kA. Experimental results are presented.