Fuel mass is one of the main economical and technical restrictions while designing space propulsion systems. Given the high costs related to the transport of mass into space, the necessary fuel mass for accomplishment of the mission should be minimized. For an optimum thrust/fuel consumption ratio the gas exit velocity must be maximized. In this research this is achieved through the heating of the micro gas flow by an electrical arc inside the sub-sonic region of the propulsion system. The electrical arc induces a partial ionization of the propellant gas. Because of the very low mass flow the gap of the plasma channel has a width of just a few hundred microns. The electrical arc consists of electrons being accelerated through this small gap by the charged walls of the microchannel. The electrons move in a cross flow compared to the propellant gas.

In order to study this approach an experimental rig is built up inside a vacuum chamber. The relation between electrical power and mechanical pressurization is investigated experimentally. The won data are compared with computational results of the electrodynamic behavior inside the micro gap. The computational model consists of the coupling of the micro gas flow in the trans-sonic thruster application (e.g. [1]) with the heating mechanism of the electron motion including the partial ionization of the subsonic flow of the electric propulsion system.

The computational results are validated with the experimental data. Through this investigation a very efficient form of electrodynamic heating-modeling is developed. The very good results show the quality of the present method and encourage further utilization and development. For this reason this model will be used for the optimization and the computational engineering pre-development of future thermo-electric propulsion systems.

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