Targeted Electrospray Performance for High Efficiency and Scalability

Electrospray thrusters are superior to plasma based electric propulsion with respect to thrust efficiency and thrust to power ratios (T/P), with difficulties predominantly being scaling to high power applications. Specifically, Busek contends that such applications require more conventional propellant delivery mechanisms, which include latching and proportional flow control valves to manage the large amounts of propellant commensurate with kW-level electrospray propulsion. As part of the Lisa Pathfinder mission, Busek has flight qualified and demonstrated on orbit such a feedsystem. Busek proposes to develop a modularized electrospray emitter design suitable for production of arrays that are tailored for attachment to pressurized propellant sources. Thruster performance shall be optimized for high efficiency and T/P, targeting emission of small ion clusters. A four emitter array (~20W) shall be demonstrated in the Phase I, with scaling to 100W or greater performed during the Phase II effort, and larger systems produced from additional stacking and/or scaling. Additionally, using novel power converter technology, Busek shall demonstrate increased high voltage generation efficiency, a key requirement for attaining system efficiencies approaching 70%. Lessons learned will be implemented to develop scaling laws and designs necessary to approach the desired power levels in subsequent efforts.