Two-point motional Stark effect diagnostic for Madison Symmetric Torus

Ko, J. and Den Hartog, D. J. and Caspary, K. J. and Den Hartog, E. A. and Pablant, N. A. and Summers, H. P. (2010) Two-point motional Stark effect diagnostic for Madison Symmetric Torus. Review of Scientific Instruments, 81 (10). pp. 1-3. ISSN 0034-6748

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    Abstract

    A high-precision spectral motional Stark effect (MSE) diagnostic provides internal magnetic field measurements for Madison Symmetric Torus (MST) plasmas. Currently, MST uses two spatial views-on the magnetic axis and on the midminor (off-axis) radius, the latter added recently. A new analysis scheme has been developed to infer both the pitch angle and the magnitude of the magnetic field from MSE spectra. Systematic errors are reduced by using atomic data from atomic data and analysis structure in the fit. Reconstructed current density and safety factor profiles are more strongly and globally constrained with the addition of the off-axis radius measurement than with the on-axis one only.