The study of plasma clouds around large active space structures

Large spacecraft such as the Space Shuttle perturb the natural environment by releasing contaminants into the atmosphere through outgassing, chemical dumps, and thruster firings. A fluid model was developed to describe the large scale structure of the contminant plasma cloud. The model is two dimensional with the structure along the magnetic field being averaged out. The model predicts that an important parameter is the parallel length scale of the cloud since this determines the effective length over which electrons can be drawn to short out the ions flowing perpendicular to the magnetic field. In addition, a significant amount of work was done on the small scale kinetic processes that occur in the contaminant cloud and that cannot be explained by the fluid model. These small scale processes include instabilities in the cloud, ion acceleration by the cloud and anomalies ionization in the cloud.