Implementing general moment equations for parallel closures in NIMROD

At low collisionality, valid parallel closures can be obtained by solving the first order drift kinetic equation. A previous study solved the drift kinetic equation in NIMROD code and calculated neoclassical quantities in an axisymmetric tokamak [1]. In this study, general parallel moment equations [2] are implemented in NIMROD for obtaining parallel closures. The parallel closures are applied to time-dependent fluid equations in NIMROD. The convergence of the numerical solution is shown by increasing the number of moments of the system. As a benchmark test, ion parallel flow calculations are compared to the previous study [1].



[1] E. D. Held, S. E. Kruger, J.-Y. Ji, E. A. Belli, and B. C. Lyons, “Verification of continuum drift kinetic equation solvers in nimrod", Physics of Plasmas, vol. 22, 032511 (2015)

[2] J. -Y. Ji and E. D. Held, “A framework for moment equations for magnetized plasmas", Physics of Plasmas, vol. 21, 042102 (2014)