Thorman, AlexMichael, CliveHoward, JohnBrian, VictorHolcomb, ChristopherAllen, S L2020-11-052020-11-050034-6748http://hdl.handle.net/1885/214017A motional Stark effect (MSE) imaging diagnostic was benchmarked against existing conventional MSE polarimeters on the DIII-D tokamak and delivered new capabilities for measuring the magnetic pitch angle from 2 neutral beams and on the high field side of DIII-D. Line integration across flux surfaces was considerable for the radial view utilised; nevertheless, the imaging MSE measurements from both beams were self-consistent and in close agreement with conventional MSE measurements. The ferroelectric liquid crystal waveplate used in the imaging polarimeter was discovered to have spatially non-uniform retardance; hence, it is necessary for the calibration source to replicate the ray paths of the neutral beam emission through the optical system.application/pdfen-AU© 2018 Author(s)201810.1063/1.50389692020-07-06