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Characterization of current profile reconstruction methods and application to tearing stability analyses of ITER baseline scenario discharges in DIII-D

POSTER

Abstract

We analyze edge current density (J) profile reconstructions and their uncertainties across 300 DIII-D ITER Baseline Scenario (IBS) plasmas, focusing on their role in neoclassical tearing mode (NTM) stability. Reconstructed J profiles often exhibit an edge-localized minimum or "well," arising from the interplay between inductive and bootstrap currents, whose gradients may influence NTM stability. Although reconstructions using different diagnostic suites (e.g. magnetics, MSE, Charge Exchange Recombination, Thomson Scattering) and constraints reproduce internal pitch angle measurements from the Motional Stark Effect (MSE) diagnostic, they disagree on the depth and location of the well—indicating that MSE-constrained reconstructions do not adequately resolve this feature in the examined database. Direct analysis of raw MSE data suggests the spatial resolution may not be sufficient to constrain the presence or shape of the well, and MSE signals as well as automatic kinetic reconstructions (CAKE) appear largely insensitive to H-mode access variations intended to modify edge current and tearing stability. Comparisons of J profiles in NTM-stable and NTM-onset time windows show no consistent correlation between the J well and the stability across different reconstruction methods. In contrast, plasma rotation profiles measured by charge exchange recombination show a more robust association with NTM onset in the same dataset.

Publication: Planning a paper

Presenters

  • Peggy P Li

    University of California, Irvine

Authors

  • Peggy P Li

    University of California, Irvine

  • Laszlo Bardoczi

    University of California, Irvine

  • Brian S Victor

    Lawrence Livermore National Laboratory

  • Ashton C Brown

    University of California, Irvine

  • Derek Chow

    University of California, Irvine, University of California, Los Angeles

  • Jackson Monahan

    University of California, Irvine