Predictive modeling of NSTX discharges with the updated multi-mode anomalous transport module
T. Rafiq, C. Wilson, C. Clauser, E. Schuster, J. Weiland, J. Anderson, S. Kaye, A. Pankin, B. LeBlanc, R. Bell
Nuclear Fusion 64 (2024) 076024 (11pp)
Abstract
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The objective of this study is twofold: firstly, to demonstrate the consistency between the
anomalous transport results produced by updated Multi-Mode Model (MMM) version 9.0.4 and
those obtained through gyrokinetic simulations; and secondly, to showcase MMM’s ability to
predict electron and ion temperature profiles in low aspect ratio, high beta NSTX discharges.
MMM encompasses a range of transport mechanisms driven by electron and ion temperature
gradients, trapped electrons, kinetic ballooning, peeling, microtearing, and drift resistive inertial
ballooning modes. These modes within MMM are being verified through corresponding
gyrokinetic results. The modes that potentially contribute to ion thermal transport are stable in
MMM, aligning with both experimental data and findings from linear CGYRO simulations. The
isotope effects on these modes are also studied and higher mass is found to be stabilizing,
consistent with the experimental trend. The electron thermal power across the flux surface is
computed within MMM and compared to experimental measurements and nonlinear CGYRO
simulation results. Specifically, the electron temperature gradient modes (ETGM) within MMM
account for 2.0 MW of thermal power, consistent with experimental findings. It is noteworthy
that the ETGM model requires approximately 5.0 ms of computation time on a standard desktop,
while nonlinear CGYRO simulations necessitate 8.0 h on 8 K cores. MMM proves to be highly
computationally efficient, a crucial attribute for various applications, including real-time
control, tokamak scenario optimization, and uncertainty quantification of experimental data.