Carbon Cold Cathode Electron Sources for Low Power Electric Propulsion Thrusters

The innovation proposed here is the use of carbon thin film cathodes as an electron source for electric propulsion for microspacecraft applications. Hall and ion thrusters are two types of electric propulsion systems that are commonly used on earth-orbiting spacecraft and very recently on interplanetary probes. These propulsion systems use hollow cathodes to thermionically emit electrons that are used for propellant ionization and ion beam neutralization. These cathodes require propellants and heaters that place lower limits on their size and power scalability and efficiency. Field emission cathodes compatible with electric propulsion systems will fill voids in electric propulsion technology that are needed for deep-space microspacecraft applications. Other field emission electron sources such as metal microtip cathodes are unstable and strongly susceptible to damage in the thruster ion environment. Preliminary tests on carbon film cathodes show them to be much more robust. We propose to demonstrate the feasibility of using carbon cathodes in electric propulsion systems for microspacecraft applications.