April 4-6

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Author: Tyler Markham
Requested Type: Poster
Submitted: 2022-03-04 13:59:35

Co-authors: E. D. Held, A. Spencer

Contact Info:
Utah State University
549 Greenview Loop
Logan, UT   84341
United States

Abstract Text:
The ultimate goal of this research is to couple NIMROD's continuum kinetic RE solver to its evolving fluid model for consistent simulation of runaway electron (RE) effects during disruptions. In this work we verify several 2D phase-space benchmarks involving the linear and nonlinear relativistic Coulomb collision operators which have been implemented in the NIMROD plasma fluid code. We show that the linear operator does not conserve momentum or energy for cases involving a diffuse, relativistic population relaxing back to a non-relativistic background plasma. This is then compared to the Braams-Karney potential formulation of the Beliaev-Budker operator, which is the relativistic analogue to the Rosenbluth potential formulation of the Landau operator. Legendre coefficients of these potentials are solved analytically via Green's functions and then integrated with Romberg integration to implement in NIMROD. Finally, we show successful benchmarking of the NIMROD and NORSE codes on the collisional relaxation of a two-maxwellian initial state and the distortion-induced transition to electron slide-away.

A. Stahl, M. Landreman, O. Embréus, and T. Fülöpa, Computer Physics Communications 212 (2017) 269–279.

Bastiaan J. Braams, and Charles F. F. Karney, Physics of Fluids B: Plasma Physics 1, 1355 (1989).

Work supported by the DOE under grant no.DE-SC0018146