Plasma Profile Prediction in NSTX Discharges Using the Updated Multi-Mode Anomalous Transport Module

T. Rafiq, C. Wilson, C.F. Clauser, E. Schuster, J. Weiland, J. Anderson, S. Kaye, A. Pankin, B. LeBlanc, R. Bell

29th IAEA Fusion Energy Conference

London, UK, October 16-21, 2023

Abstract

The objective of this study is twofold: firstly, to demonstrate the consistency between the anomalous transport re- sults produced by updated Multi-Mode Model (MMM) version 9.1 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 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 sim- ulation 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 compu- tation time on a standard desktop, while nonlinear CGYRO simulations necessitate 8.0 hours 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.