Computational multi-fluid model for partially ionized and magnetized plasma

In the present work, we present a computational model for studying partially ionized plasmas in thermal nonequilibrium under the effect of electromagnetic fields, such as in astrophysics or fusion-related applications. In order to tackle the non-equilibrium effects present in such a plasma, we adopt a multi-fluid formulation including electromagnetic effects. Multi-fluid equations consider each species within the mixture as behaving as different fluids, interacting among each other by means of collisions and chemical reactions. In the present article, we will extend previous efforts (with a two-fluid model)³⁴ and consider a three-fluid model, accounting for ions, electrons and neutral species. The derivation of the multi-fluid model is presented, as well as different models for the average transfer of momentum and energy in collisions are discussed. The resulting equations are coupled to the full Maxwell’s equations in order to capture phenomena such as electromagnetic waves or charge separation effects, neglected in standard magnetohydrodynamics (MHD) simulations. Our computational model will be used to simulate an electromagnetic plasma shock which have been proposed in recent literature and for which reference numerical simulations are available without account for collisional and partially ionized effects.