Fluctuation-induced electron transport in closed-drift Hall discharges

Summary form only given. Hall discharges are presently under development for use in space propulsion applications. These discharges exhibit characteristic cross-field transport, which is enhanced by fluctuations in the electric field and plasma density. Our recent electrostatic probe and laser-induced fluorescence measurements in closed-drift coaxial geometry discharges indicate that the effective Hall parameter ranges from 1-20. This value is much less than that based on classical electron transport, and while it brackets the value typical of anomalous Bohm transport, it is found to vary significantly along the axial direction of the discharge, increasing to unusually low values near the anode. In this paper, we shall present a comprehensive analysis of a large collection of data, which allows the determination of the effective Hall parameter from measured steady-state discharge properties along the channel. The dispersion characteristics of these fluctuations, believed to be responsible for the unusually low Hall parameters, are studied with negatively-biased ion collection probes. The measured oscillatory behavior of these discharges are interpreted using a linear perturbation analysis of the governing fluid equations for a magnetized, cylindrical plasma in which there are axial gradients in the plasma properties.