Tangential multi-color ``optical'' soft X-ray array for electron temperature and transport measurements

A multi-color ``optical'' soft X-ray array is being prototyped on NSTX for fast ($\leq$0.1 ms) measurements of the electron temperature profile, heat and particle transport, and MHD activity. Tests of a single-color array indicate that the optical device can have a signal-to-noise ratio superior to that of diode arrays. In addition, due to the compact nature of the diagnostic the plasma access is improved. We designed, built, and tested on NSTX, a tangential 48-channel ``optical'' soft X-ray array which views the same plasma volume at the mid-plane, in three different energy ranges determined by different SXR metallic foils. Depending on the electronics to be used, the diagnostic can have a time resolution ranging from a few $\mu$s to $\sim$0.1 ms, with spatial coverage from 0$\leq$r$\leq$1. We plan to obtain space and time resolved electron temperature measurements for perturbative transport studies. Initial results from a range of operational regimes in NSTX will be presented.