Disruption Opportunity
Today’s spacecraft electric propulsion systems, such as Hall thrusters, use thermionic cathodes to ignite, sustain, and neutralize an ion beam. These hot cathodes operate on noble gases with delicate chemistry that poison (fail) rapidly in trace amounts of air or water.
The Cathode Advancements in Science and Technology for Oxygen Resistance (CASTOR) program targets a compact, long-lived, efficient electron source for spacecraft EP systems operating on oxygenic species, capable of supplying from one to tens of amperes electrical current. The goal is a cathode that can operate using purely air or water as the main working fluid while matching today’s noble gas performance.
CASTOR focuses on air and water as ubiquitous but extremely challenging oxygenic species, where success will extend the operating envelope of EP systems to the broadest possible range of alternative fuels.
The goal of CASTOR is to develop new cathodes capable of supporting EP thrusters operating on air or water for 1,000 hours or more while matching the performance of today’s cathodes operating on noble gases. Today’s spacecraft EP systems provide excellent fuel efficiency by accelerating positively-charged ions to exhaust velocities an order of magnitude higher than chemical rockets, but most thrusters also require electron emitting cathodes to neutralize the departing ions and prevent spacecraft charging.
