April 4-6

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Author: Joseph R Jepson
Requested Type: Poster
Submitted: 2022-03-03 17:19:18

Co-authors: C.C.Hegna, E.D.Held, E.Howell

Contact Info:
University of Wisconsin - Madison
1500 Engineering Dr
Madison, WI   53706
United States

Abstract Text:
In an effort to incorporate kinetic ion physics in extended MHD simulations, a Chapman-Enskog-like (CEL) approach [1] is used in NIMROD simulations. This formulation has been successfully benchmarked against the predictions of neoclassical theory for poloidal ion flows in axisymmetric tokamak geometry [2]. The CEL implementation allows for a rigorous kinetic closure of NIMROD’s fluid model as the kinetic equation is solved for in the presence of a self-consistent background Maxwellian defined by temporally and spatially evolving density, temperature and fluid velocity. For an initial test, we have modeled the axisymmetric fluid evolution from an EFIT equilibrium based on DIII-D Iter-Baseline-Scenario (IBS) discharge 174446 at 3390 ms. For testing purposes, we initialize an MHD equilibrium in the absence of equilibrium fluid flow profiles. Due to the presence of equilibrium ion temperature gradients, neoclassical physics predicts that self-consistent ion flows will be generated. In a fluid theory, this physics is described through kinetic closure moments. In this work, the evolution of ion fluid flows is simulated for an initially static axisymmetric equilibrium until a self-consistent equilibrium state with plasma flows is developed. [1] J. J. Ramos, Physics of Plasmas textbf{17}, 082502 (2010). [2] J. R. Jepson, C. C. Hegna, E. D. Held, J. A. Spencer, and B. C. Lyons, Physics of Plasmas textbf{28}, 082503 (2021)