Development of a high order deterministic Boltzmann-Poisson solver for simulation of rarefied plasma in a low-density wind- tunnel

The DRAG-ON facility at the von Karman Institute was designed to replicate on-ground the rarefied flow conditions encountered by satellites at Very Low Earth Orbit. This facility allows to characterize intakes for Air-Breathing Electric Propulsion systems and to assess the effects of the high-speed rarefied flow on satellite components. The flow is generated by using a Particle Flow Generator, which exhausts a partially ionized plasma plume with ions reaching orbital speeds. Such a flow presents significant modelling challenges because of the charged particles, reactive collisions, and low densities involved. This proposal aims to address the challenges posed by such highly non-equilibrium conditions. The proposed approach is to simulate the plasma with a deterministic Boltzmann-Poisson solver, as opposed to the stochastic methods usually used for such problems. The latter introduce noise in the solution, which is an important limitation particularly when there is the desire to accurately simulate chemistry. The development of the solver will be the main task of this work. This constitutes a challenge because of the high dimensionality of the problem, the integro-differential nature of the equation, and the high level of fidelity targeted. The current project will extend the application domain of deterministic Boltzmann solvers by including multiple charged species and chemical reactions. In addition, the presence of electrons alongside heavy particles introduces a large mass disparity, which requires specific numerical method developments. The planned approach for an efficient implementation is to exploit fast spectral methods for the discretization of the velocity space, and high order Discontinuous Galerkin discretization of the physical space. Before the development of the solver, proper modelling will be performed to select the relevant processes to include. Finally, the DRAG-ON facility will provide a unique environment to validate the simulation results.