Initial measurements from the new radial x-ray spectrometer on MST

X-ray spectra in the MST are used to investigate the transport of energetic electrons and to estimate the effective ionic charge, $Z_{\mathrm{eff}}$. The x-ray diagnostic consists of six Amptek XR-100CR detectors, each of which can be placed on any of 17 ports covering $\frac{r}{a}$ values from 0.87 inboard to 0.84 outboard. The detectors are connected to Cremat Gaussian shaping amplifiers with a shaping time of $500\,\mathrm{ns}$. The shaping amplifier output is digitized, and a new code is used to identify the times and amplitudes of the pulses. With this configuration, in the best case, an x-ray spectrum can be generated for time periods of one millisecond or less. Measurements have been taken in quasi-single helicity plasmas over MST's entire range of plasma currents. Work has begun on modeling $D_{r}$ and $Z_{\mathrm{eff}}$ radial profiles using the CQL3D code constrained by measured x-ray spectra.