A versatile multi-energy soft x-ray diagnostic for Te measurements in the Madison Symmetric Torus

A multi-energy soft x-ray (ME-SXR) diagnostic based on the PILATUS3 100K x-ray camera, produced commercially by DECTRIS Ltd., has been installed on the Madison Symmetric Torus (MST) reversed-field pinch. This photon-counting camera consists of a two-dimensional array of ∼100,000 pixels for which the lower photon absorption cutoff energy can be independently set. This allows it to be configured for a unique combination of simultaneous spatial and spectral resolution. First plasma data has now been collected, and challenges with detector saturation have been sucessfully resolved. Analysis is complicated by the presence of bright Al+11 and Al+12 emission lines at ∼2 keV. In order to properly interpret this data a full forward model has been developed which produces realistic chord-integrated ME-SXR synthetic measurement given the underlying Te, ne, neutral density, and impurity density profiles. A method for using this model in a Bayesian framework to extract equilibrium Te measurements from MST high-temperature plasma data is presented. Resulting profiles show good agreement with Thomson scattering measurements in the core.