April 15-17

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Abstracts

Author: J. Andrew Spencer
Requested Type: Poster
Submitted: 2019-02-22 12:31:58

Co-authors: E.D.Held, J.Ji

Contact Info:
Utah State University
4415 Old Main Hill
Logan, Utah   84322-4
United States

Abstract Text:
The Chapman-Enskog like method is used to close the fluid equations. The formulated equations describe the simultaneous evolution of the fluid quantities and non-Maxwellian portion of the distribution function in the long mean free path regime of magnetized plasmas. We discuss a continuum numerical solution to these equations implemented in the NIMROD code. We express the distribution function in velocity coordinates using pitch-angle and speed normalized by the local thermal speed. As a result, the temperature and kinetic distortion are tightly coupled and demand a careful treatment of the implicit advance of both over large time steps. Newton's method is used to solve the nonlinear equations for the temperature and kinetic distortion simultaneously. We evaluate the computational efficiency of the code and required velocity space resolution. We compare some preconditioning strategies. Results are presented for applications involving equilibration along field lines which leads to temperature flattening across magnetic islands in slab, cylindrical and toroidal geometry.

Work supported by DOE under grant nos. DE-FC02-08ER54973, DE-FG02-04ER54746, and DE-SC0018146.

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