The Effects of Cathode Configuration on Hall Thruster Cluster Plume Properties

Clusters of Hall thrusters are being considered for use on a variety of missions requiring electric propulsion systems capable of operating at power levels in excess of the current state of the art. One of the key factors to be considered in determining the optimum cluster architecture is the configuration of the electron-emitting cathode(s). This work presents experimentally determined plume properties and discharge current characteristics obtained with multiple thrusters coupled to a single cathode. Spatially resolved plasma density, electron temperature, and plasma potential data are presented during both single thruster and cluster operation. Measurements taken in this configuration are compared to previously published data obtained with each thruster coupled to its own independent cathode. Significant differences between the two configurations are noted and explained. Additionally, critical plasma parameters in the cluster plume are shown to be strongly influenced by the location of the hollow cathode.