|approved||slides.pdf||2018-05-02 08:06:10||J. Andrew Spencer|
Author: J. Andrew Spencer
Requested Type: Poster
Submitted: 2018-03-01 18:48:18
Co-authors: Eric D. Held, Brett Adair, Jeong-Young Ji
Utah State University
4415 Old Main Hill
Logan, Utah 84322-4
The Chapman-Enskog like electron drift kinetic equation** provides kinetic closure of fluid equations and extends to the long mean free path regime of magnetized plasmas. In this work we discuss the application of a continuum numerical solution to this equation to provide closures for the NIMROD code. Accuracy of the solution is aided by expressing the equation in velocity coordinates using pitch-angle and speed normalized by the thermal speed. This tightly couples the temperature to the kinetic distortion, and demands a careful treatment of the time-centering to implicitly advance both over large time steps. Comparisons are presented for three approaches: 1) leapfrog integration, 2) Picard iteration, and 3) simultaneous semi-implicit integration. Comparisons are made of computational efficiency and required velocity space resolution. 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.
**J. J. Ramos, Phys Plasmas 17, 082502 (2010).