Algorithm Development for the Two-Fluid Plasma Model

Abstract

Abstract : An algorithm is developed based on the multi-fluid plasma model derived from moments of the Boltzmann equation. Large mass differences between electrons and ions introduce disparate temporal and spatial scales and require a numerical algorithm with sufficient accuracy to capture the multiple scales. The multi-fluid capability is not limited to two species. Plasma with multiple components can be modeled, e.g. impurity ions, neutral gas. The multi-fluid equations are derived in divergence form for the naturally occurring conserved variables. The source terms of the multi-fluid plasma model couple the fluids to themselves (interspecies interactions) and to the electromagnetic fields. The solution and evolution must be tightly coupled to prevent unstable numerical oscillations. A discontinuous Galerkin method is developed to solve the governing equations on a computational grid and to simulate plasma phenomena. Interspecies interactions also occur through collisional source terms that account for the direct transfer of momentum and energy. In addition to the plasma and electrodynamic physics, the multi-fluid plasma model captures atomic physics in the form reaction rate equations for ionization and recombination, which introduce new temporal scales to the plasma dynamics model.