Abstract Details
Abstracts
Author: David A Arnold
Requested Type: Poster
Submitted: 2024-04-12 16:17:12
Co-authors: R.N. Chandra, N.J. DaSilva, C.J. Hansen, J.P. Levesque, Boting Li, M.E. Mauel, M.N. Notis
Contact Info:
Columbia University
500 W 120th St
New York, NY 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 of 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 non-disruptive, saturated, mode activity consistent with experimental data. Effects of varying wall resistivity with toroidal mode number are investigated in the context of a saturated resistive wall mode with magnetic islands. Variation in mode structure across differing thermal transport coefficients is also discussed. Baseline simulations of sawtoothing activity are also established with different macroscopic transport coefficients and current ramping rates for future comparison to experimentally measured instabilities. Work on improving boundary conditions in the resistive wall model to capture large-scale n=0 equilibrium evolution during disruptions is shown. 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 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)
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