Fast electron studies using a multichord x-ray spectrometer on MST

The X-ray spectroscopy diagnostic on MST consists of six SXR detectors and six HXR detectors capable of measuring photons in the energy range $3-25\ \mathrm{keV}$ and $10-60\ \mathrm{keV}$, respectively. The detectors can be installed on any of $17$ ports viewing a poloidal cross-section, with impact parameters from $\frac{r}{a}=0.87$ inboard to $\frac{r}{a}=0.84$ outboard. An updated code processes the digitized signals, providing the time and energy of photons incident on each detector, and is capable of resolving individual photons arriving at the detector less than $50\ \mathrm{ns}$ apart. The spatial resolution of the system may allow improved diagnosis of the QSH tearing mode on MST, including the x-ray enhancement and spatial structure. The system may be able to probe electron heating during magnetic reconnection, the counterpart to noncollisional ion heating observed during magnetic reconnection on MST. X-ray flux from multiple view chords are compared with prediction from the kinetic code CQL3D. X-ray measurements can be used to constrain CQL3D in order to estimate $Z_{\mathrm{eff}}$ and radial diffusion profiles. Additionally, radially-localized x-ray measurements from lower hybrid current drive experiments are shown.