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Author: Brendan C Lyons
Requested Type: Poster
Submitted: 2018-03-01 12:48:08

Co-authors: N.M. Ferraro, S.C. Jardin, J.J. Ramos, C.C. Kim, L.L. Lao, Y.Q. Liu

Contact Info:
General Atomics
PO Box 85608
San Diego, California   92186-5

Abstract Text:
The risk of damage in future tokamaks necessitates high-fidelity simulations to predict disruption avoidance and mitigation. While the macroscopic evolution of transient events is largely governed by magnetohydrodynamic (MHD) forces, disruption onset and dynamics are frequently influenced by additional physics, including neoclassical kinetics and impurity radiation. In order to perform the required integrated modeling to capture all of these effects, we begin with the M3D-C1 code, which solves the nonlinear, two-fluid MHD equations in three-dimensional toroidal geometry. We explore two planned extensions to M3D-C1 for the purpose of disruption dynamics and mitigation modeling. First, a new drift-kinetic-equation (DKE) solver is being developed in which the perturbed, non-axisymmetric distribution function is driven by linear MHD perturbations. This code will be coupled to M3D-C1 in order to provide neoclassical corrections to linear MHD instabilities (e.g., resistive-wall modes). The new code will be based on the formalism of the DK4D axisymmetric DKE solver, though planned numerical advances will also be discussed. Second, the KPRAD code has been coupled to M3D-C1 in order to calculate ionization, recombination, and radiation for impurities. An initial single-fluid implementation, reduced from the full multi-fluid equations, will be discussed. Results from 2D nonlinear simulations with distributed impurity profiles will be benchmarked against NIMROD modeling. In addition, plans for 3D modeling will be presented. This work represents the first step in a disruption-mitigation study using M3D-C1 to model shattered and shell-pellet injection.

This work is supported by the US DOE grant numbers DE-FG02-95ER54309 and DE-FC02-06ER54873, along with the SciDAC Center for Tokamak Transients Simulations (DE-SC0018109).