Updated and expanded S-scaling and validation studies on the MST RFP

Disruptions in tokamaks and self-organization in RFPs are governed by nonlinear MHD processes that are encoded into computational models. The objectives of the study are to perform MHD validation experiments on RFPs in the MST device, focusing on magnetic fluctuation behavior and its scaling with Lundquist number, S, and to make validation metric comparisons between experimental and nonlinear extended MHD simulation results. Nonlinear MHD simulations have been run with single-fluid NIMROD and DEBS codes. RFP experiments were performed on MST including at newly-accessible low-current values using a programmable power supply. The results from both simulations and experiment were fit to b=cS^α, where b is the magnetic field fluctuation amplitude. These fits give α values around -0.2, within statistical uncertainties, and respective c values match within uncertainties. New experiments will scan over S∼T_e^3/2, where T_e, is the electron temperature. Straylight mitigation has recently enabled Thomson scattering temperature measurements across an entire minor radial profile, including at the plasma edge. Validation metric comparisons and integrated data analysis techniques are applied to these data.