The multi-fluid plasma model only assumes local thermodynamic equilibrium within each fluid, e.g. ion and electron fluids for the two-fluid plasma model. Derivation of the MHD model involves several asymptotic and simplifying assumptions that can limit its applicability. Therefore, the two-fluid plasma model more accurately represents the appropriate physical processes. Physical parameters indicate the importance of the two-fluid effects: electron to ion mass ratio m e /m i , ion skin depth δ i , and ion Larmor radius r L . The MHD model assumes m e /m i = 0, δ i = 0, and r L = 0. Asymptotic approximations of the two-fluid model, Hall-MHD, has an unbounded Whistler wave that requires artificial dissipation. No unbounded waves exist in the two-fluid model. An algorithm is developed for the simulation of plasma dynamics using the two-fluid and multi-fluid plasma models. The algorithm implements a discontinuous Galerkin method that uses an approximate Riemann solver[1] to compute the fluxes of the fluids and electromagnetic fields at the computational cell interfaces. The two-fluid plasma model has time scales on the order of the electron and ion cyclotron frequencies, the electron and ion plasma frequencies, the electron and ion sound speeds, and the speed of light. Such disparate time scales motivate a semi-implicit time-stepping scheme to overcome the severe time step restrictions of explicit schemes. The algorithm is validated with several test problems including the GEM challenge magnetic reconnection problem [2] and the generation of dispersive plasma waves which are compared to analytical dispersion diagrams. The algorithm is applicable to study advanced physics calculations of plasma dynamics including magnetic plasma confinement and astrophysical plasmas. Three-dimensional solutions of the Z-pinch and the field reversed configuration (FRC) magnetic plasma confinement configurations are presented.

Modulated heating of the lower ionosphere with the HAARP HF heater is used to excite 1–2 kHz signals observed on a ship‐borne receiver in the geomagnetic conjugate hemisphere after propagating as ducted whistler‐mode signals. These 1‐hop signals are believed to be amplified, and are accompanied by triggered emissions. Simultaneous observations near (∼30 km) HAARP show 2‐hop signals which travel to the northern hemisphere upon reflection from the ionosphere in the south. Multiple reflected signals, up to 10‐hop, are detected, with the signal dispersing and evolving in shape, indicative of re‐amplification and re‐triggering of emissions during successive traversals of the equatorial interaction regions.

A continuum kinetic model for plasma based on the Vlasov-Maxwell system for multiple particle species is developed. Consideration is added for boundary conditions in a truncated velocity domain and supporting wall interactions. A scheme to scale the velocity domain for multiple particle species with different temperatures and particle mass while sharing one computational mesh is described. A method for assessing the degree to which the kinetic solution differs from a Maxwell-Boltzmann distribution is introduced and tested on a thoroughly studied test case.The discontinuous Galerkin numerical method is extended for efficient solution of hyperbolic conservation laws in five or more particle phase-space dimensions using tensor-product hypercube elements with arbitrary polynomial order. A scheme for velocity moment integration is integrated as required for coupling between the plasma species and electromagnetic waves.A new high performance simulation code WARPM is developed to efficiently implement the model and numerical method on emerging many-core supercomputing architectures.WARPM uses the OpenCL programming model for computational kernels and task parallelism to overlap computation with communication. WARPM single-node performance and parallel scaling efficiency are analyzed with bottlenecks identified guiding future directions for the implementation.The plasma modeling capability is validated against physical problems with analytic solutions and well established benchmark problems.