Valentina Pessina (Plasma Technology & Basics of Electrical Engineering, UniBwM)
This project aims to establish a robust and efficient simulation framework based on the Direct Simulation Monte Carlo (DSMC) Method for the Air-Breathing Electric Propulsion System (ABEP) development targeting the low orbits of Earth and Mars. These space propulsion systems are meant to keep satellites in low orbit where the atmosphere is sufficiently dense to provide the required gas density. The ABEP system collects the propellant directly from the atmosphere, the collected atmospheric particles are ionized, and finally, the energized particles are ejected from the system, thus providing the thrust by the second law of motion. Hence, an onboard tank is not required since the propellant is collected directly from the surroundings.
Although the development of ABEP is carried out mainly through ground tests, the computational tools can provide valuable insight into vital aspects to keep the system in orbit, such as the drag to be compensated by the thruster or the intake collection efficiency. The DSMC simulations can successfully cover the complexity of the phenomena experienced by the orbiting satellite and the altitude-dependent parameters, such as the atmospheric composition, the gas temperature and density, and the mean free molecular path, hence the Knudsen number. In addition, depending on the altitude, the gas rarefaction, and the atmospheric composition the surface-particle collisions become statistically more relevant than the intermolecular collisions. For this reason, the correct description of the Gas-Surface-Interaction (GSI) is essential because of its relevance in energy and momentum exchange and its direct impact on drag esteem. The effect of the GSI modeling on the estimation of the drag and intake collection parameters is investigated by comparing the results yielded by the following models: purely specular reflection, the Maxwellian partially diffusive reflection, and finally the model proposed by Cercignani, Lampis, and Lord. The selected solver is the Stochastic PArallel Rarefied-gas Time-accurate Analyzer (SPARTA) with several features, such as the possibility of local refinement of the cartesian grid for an efficient local grid adaptation, implementation of relevant chemical and physical advanced models (gas-surface interaction, chemical reactions, including ionization), and finally the high parallelization.