The Aerospace Laboratory for Plasma Experiments (ALPE) at Western Michigan University (WMU) has been focused on the development of plasma diagnostics for use in the evaluation of propellants for and analysis of electric propulsion (EP) devices. Two diagnostic platforms will be discussed. Ion energy distribution functions in the plume of a Hall thruster can be determined with a Retarding Potential Analyzer (RPA). This practice is common for EP devices; however, it traditionally only provides time averaged data. A high speed RPA has been developed for evaluation of the temporal evolution of ion energy, providing valuable information about how ion velocities change as a function of time in the plume of an EP thruster. Secondly, a plasma diagnostic platform has been developed to study the decomposition and ionization of ionic liquids for use in EP devices. A decomposition /ionization chamber is connected to an optically accessible chamber. Planar laser induced fluorescence (PLIF) and Raman spectroscopy are performed on the propellant to determine the species present after decomposition and ionization. Downstream, a mass analyzer provides information on final products.
Dr. Kristina Lemmer
Associate Professor in the Department of Mechanical and Aerospace Engineering at Western Michigan University where she has wide and varying research interests. Kristina received her undergraduate and graduate degrees from the University of Michigan in Aerospace Engineering. Her current research interests include alternative propellants for electric propulsion systems, oscillations in magnetically shielded Hall thrusters, instant start, and high powered hollow cathodes, integration of electric propulsion systems with nanosatellites, small satellite design and integration, plasma-assisted combustion, and diagnostic development for plasma research. Dr. Lemmer’s research is supported by the AFOSR, NASA, and NSF. She is a past recipient of AFOSR’s Young Investigator Program grant.