Self-regenerating Nanotips: Indestructable Field-emission Cathodes for Low-power Electric Propulsion

This research focuses on a field-emission cathode for use in Electric Propulsion EP that has the potential for very long lifetime due to its ability to be re-generated when the emitter tip becomes damaged. The field-emitting tips were formed by the application of an ionextracting electric potential applied to a heated indium-coated tungsten needle, known as a liquid metal ion source LMIS. The LMIS is then cooled, freezing in a solid nanotip at the apex. When the modified needle was then subjected to electron-extracting potentials stable and long-lived electron emission was observed. The focus of this investigation was to operate and quench a LMIS at ion emission currents from 2 to 25 A to acquire micrographs of the surface morphology as a function of the ion emission current at quench. The LMISs were also tested against representative state-of-the-art field emitters that were made from tungsten.