Influence of Gas-Surface Interaction Models on Predicted Performance of a Micro-Resistojet.

摘要

The Free Molecule Micro-Resistojet was designed as a micropropulsion system capable of performing attitude control and primary maneuvers for nanospacecraft with a mass of less than or equal to 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 parametrically assess the performance of a typical thruster geometry using a general Maxwell scattering model and two versions of the Cercignani-Lampis-Lord 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.