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ABSTRACTThis report describes progress, in experimental development, plasma diagnostics, and modeling, in advanced pulsed plasma thrusters (PPT) for application to formation-flying satellite constellations such as TechSat21. The research concentrated on coaxial Teflon PPTs, predominantly of the electrothermal (high thrust) type, with an average power of 100 watts. During this effort, performance advances were made both in the thruster design and in the pulsed circuitry driving the discharge, aided by increased understanding derived from a two-fluid model. The results of this research led to the development, under separate contract to CU Aerospace, of a PPT flight test model (PPT-8) which was tested at the AFRL Electric Propulsion Laboratory.
SUBJECT TERMSElectric propulsion, Pulsed thruster, Teflon.
ABSTRACTThis report describes progress, in experimental development, plasma diagnostics, and modeling, in advanced pulsed plasma thrusters (PPT) for application to formation-flying satellite constellations. The research concentrated on coaxial Teflon PPTs, predominantly of the electrothermal (high thrust) type, with an average power of 100 watts. During this effort, performance advances were made both in the thruster design and in the pulsed circuitry driving the discharge, aided by increased understanding derived from a two-fluid model. The results of this research led to the development, under separate contract to CU Aerospace, of a PPT flight test model (PPT-8) which was tested at the AFRL Electric Propulsion Laboratory.Experiments are performed on a cylindrically-symmetric Teflon electrothermal thruster with variable geometry, energy and pulse rate. Measurements are made of pulse energy and current, mass loss, impulse bit, and heat loss. The results show that the specific mass loss is linear with cavity length, and roughly independent of energy. The specific thrust is roughly constant with energy (> 35 _N-s/J) for high energies, but decreases somewhat for low energies. The highest specific impulse is achieved with the shortest cavity length. Comparison with a two-stream model suggests that the fraction of late-time ablation is on the order of 10%, compared to 40% for the LES-8/9 thruster, and that a rarefaction wave model can be used to predict the impulse bit with an empirically-determined proportionality constant. Heat loss measur...
