Abstract Details
Abstracts
Author: David A Arnold
Requested Type: Poster
Submitted: 2025-03-14 02:08:18
Co-authors: C. J. Hansen, J. P. Levesque, R. N. Chandra, Boting Li, A. R. Saperstein, M. E. Mauel, G. A. Navratil
Contact Info:
Columbia University
500 W 120th St
New York, New York 10027
United States
Abstract Text:
The NIMROD [1] code is used to validate multiphysics models (MHD + resistive wall) for the prediction of mode structures and scrape-off-layer (SOL) currents in tokamaks using high-resolution current, magnetic, and optical diagnostics from HBT-EP [2]. NIMROD’s existing thin resistive wall boundary condition is extended to include non-axisymmetric wall resistivity, capturing effects of ports and other wall structures. Simulations of HBT-EP with a resistive wall observe periodic sawtoothing activity consistent with experimental data [3]. Effects of varying plasma-wall separation and wall resistivity with toroidal mode number on the corresponding critical thresholds for sawtooth suppression are investigated. Variations in sawtooth structure and disruptive behavior are also shown across differing thermal transport parameters. Work on improving boundary conditions in the resistive wall model to capture large-scale n=0 equilibrium evolution during disruptions is shown. Further work analyzing the dependence of sawtooth suppression on externally applied fields and currents in the presence of an asymmetric resistive wall will be discussed. Applications toward better understanding the 3D structure of wall-connected currents and the effects of runaway electron mitigation coil (REMC) fields will be presented. Initial validation studies of numerical models for wall-connected currents during sawtooth and disruptive activity are conducted by analyzing synthetic and experimental phase differences between diagnostic signals on HBT-EP, including current-sensing tiles and poloidal extreme-ultraviolet (EUV) arrays, with the goal of improving SOL and wall models for ITER and next-step devices.
[1] C. Sovinec et al., J. Comput. Phys. (2004)
[2] J. Levesque et al., Nucl. Fusion (2017)
[3] Boting Li et al., Nucl. Fusion (2024)
Characterization: 4.0
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