Paulo Lozano, Space Propulsion Laboratory - MIT

Because of their potential for scalability to very low power levels, electrospray thrusters operating in the pure ionic regime are an attractive technology for a variety of small spacecraft missions in low earth orbit and deep space. These thrusters are comprised of a large number of individual microscopic “emitters” that transport an ionic liquid propellant. Each one of these emitters produce and accelerate an ion beam when a strong electric field is applied at the liquid-vacuum interface. The right selection of materials and manufacturing techniques of these devices is essential to make improvements in their performance beyond what is possible today. To achieve this goal, it is important to take advantage of the recent progress made in the scientific understanding of the electrospray ion emission process. Multi-physics models are used to establish optimal geometries and operational conditions that promote stability. It is found that electrified menisci working in the pure ionic regime are exceptionally small and work stably only within a narrow range of voltages. The understanding of such behavior is essential to move towards the fabrication and testing of near-optimal emitter elements. Novel configurations could be fabricated in soft materials, not commonly used in the aggressive environment of chemical or plasma thrusters.