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DISTRIBUTION /AVAILABILITY STATEMENTApproved for public release; distribution unlimited. The Free Molecule Micro-Resistojet wils designed as a micropropulsion system capable/of performing attitude control and primary /maneuvers for nanospacecraft with^nassjjess than 10 kg. The details of gas-surface interactions between propellant molecules and surfaces held at elevated temperature are critical in predicting the propulsion system's performance and efficiency. The aim of this study is to asseST^arametrically the performance of a typical thruster geometry using a general Maxwell scattering model and two versions of the Cercignani-LampisLord model. The models are incorporated into a Direct Simulation Monte Carlo numerical code and are used to bound the predicted performance characteristics of the thruster. The total specific impulse varies by approximately 20% over range of accommodation coefficients from specular to diffuse surface scattering. However, there was only a maximum difference of about 5% between the models for a given accommodation coefficient. Other more microscopic parameters, such as axial velocity distribution functions, appear to depend more on the scattering model used.
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