Field Emission Cathodes used in the FEGI Get-Away-Special Shuttle Mission

Field emission cathodes are presently being developed as low-power space electric propulsion neutralizers and for spacecraft charge control and electrodynamic tether applications requiring no consumables. These cathodes effect cold electron emission by the application of a relatively high electric field across a small gap from some kind of electron emitting (cathode) surface. Various designs of field emission cathodes are being investigated for charge control on a student-built experiment called Field Emission Get-Away-Special Investigation (FEGI), including molybdenum, carbon nanotube, boron nitride and diamond surface emission cathodes. This paper presents the current progress of the FEGI experiment with a focus on the emitters that will be flown, and the immediately surrounding electrical, mechanical and environmental support structures.