Disruption Mitigation and Impurity Radiation Modeling with M3D-C1

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. Four different numerical and physical models of the coupling have been implemented. The model with a single temperature-evolution equation has been verified in a 2D, nonlinear benchmark with coupled NIMROD-KPRAD simulations, showing near-perfect agreement between the two codes. Simulations with two temperature equations have been performed, demonstrating longer thermal quench times due to the necessary thermal equilibration between ions and electrons. Initial results from a 3D benchmark between M3D-C1 and NIMROD will be presented, as will progress on 2D and 3D, nonlinear M3D-C1 simulations of pellet injection using ablation models of various levels of sophistication. Plans for validation against DIII-D and JET shattered-pellet injection (SPI) experiments, along with predictive simulations of ITER will also be discussed.