April 15-17

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Abstracts

Author: Brendan C Lyons
Requested Type: Poster
Submitted: 2019-02-22 20:16:00

Co-authors: N.M. Ferraro, S.C. Jardin, C.C. Kim, Y.Q. Liu, J. McClenaghan, P.B. Parks, L.L. Lao

Contact Info:
General Atomics
PO Box 85608
San Diego, CA   92109
USA

Abstract Text:
The risk of damage to future tokamaks requires robust disruption-mitigation techniques, the most promising of which uses pellet injection of impurities to radiate stored energy. In order to simulate pellet mitigation for projection to ITER and beyond, we have coupled the M3D-C1 extended-magnetohydrodynamics code to the KPRAD ionization/radiation code. A 2D, nonlinear benchmark with coupled NIMROD-KPRAD simulations shows near-perfect agreement between the two codes deep into the nonlinear phase. Three-dimensional nonlinear modeling of the benchmark case with M3D-C1 will be presented. We find that, with an axisymmetric, on-axis impurity source, the plasma remains stable throughout the thermal quench. Increased resistivity on-axis causes the current to diffuse into a thin shell. This shell eventually goes unstable to low-n modes, resulting in a pronounced current spike, the first seen of its magnitude in 3D, magnetohydrodynamic disruption modeling. Comparisons to NIMROD for this 3D benchmark will be presented. Furthermore, several variants of this 3D benchmark will be explored, including the effect of a resistive wall and the toroidal localization of the impurity source. Finally, we will present future plans for coupling to pellet-ablation models of various levels of sophistication and validation with DIII-D disruption-mitigation experiments.
Supported by the US DOE grant numbers DE-FG02-95ER54309, DE-FC02-04ER54698, and DE-SC0018109.

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