10-Moment Multi-Fluid Simulations of Anisotropic Plasmas in Magnetic Fields
Derek Kuldinow, Stanford University
High energy density plasmas, especially those which only last for short periods of time, are subject to non-equilibrium phenomena owing to the inability of individual particles to exchange information with one another quickly enough. Kinetic simulations, which capture the behavior of individual particles, are considered the highest fidelity model but can be prohibitively expensive owing to the wide range of temporal and spatial scales of interest. On the other hand, fluid simulations achieve a computational advantage by considering the ensemble of particles in a statistical sense and tracking their averaged quantities; however, a 5-moment model that solves for mass, momentum, and energy typically necessitates the assumption that the fluid is near-equilibrium. Recent experiments have measured significant anisotropies in high-energy laser-induced plasmas, which can affect plasma transport and reaction rates. Conventional fluid models cannot capture these non-equilibrium phenomena and their effects on global metrics are poorly understood. We are developing a 10-moment multi-fluid plasma model that can capture finite non-equilibrium effects through direct modelling of a full anisotropic pressure tensor. The model is applied to both high-temperature fully ionized and low-temperature partially ionized plasmas, showing the ability of the 10-moment model to capture effects previously limited to kinetic models. Future work and extensions to the model will be discussed.