Ionic liquid ion sources are being developed for space propulsion application on Cube/small satellites. To generate thrust, ionic liquid ion sources expel a plume of energetic particles that are high-energy positively and negatively charged ions. One of the biggest challenges with implementing propulsion on any type or size of spacecraft is plume-spacecraft interaction. Emitted plume ions can and will interact with spacecraft surfaces. Further, plume ions interact with materials and surfaces present in ground-based test facilities, and can lead to anomalous results that mask the true propulsion system behavior. While plume-surface interactions have been known and investigated for decades for electric propulsion systems such as gridded ion and Hall-effect thrusters, they are only beginning to be explored for emerging ionic liquid ion sources. This talk focuses on recent experiments at the University of Illinois Urbana Champaign Electric Propulsion Laboratory studying the ion-induced electron emission behavior of surfaces bombarded by ions in an [EMIM][BF4] electrospray plume. The results have application and impact on ion source ground-based testing and diagnostics, as well as spacecraft electrical configuration.
