A novel electrostatic feeding concept for liquid-fed pulsed plasma thrusters

Abstract

This work reports on the design and experimental exploration of a fully functional electrostatic pump that has potential application for space systems, such as Pulsed Plasma Thrusters (PPT). The pump can generate pressures in excess of 300 Pa, without employing moving parts. The pump prototype demonstrated operational feasibility in isolated experiments and as an integrated sub-system in a PPT-relevant testing platform.
The newly developed pump has been adapted to integrate in an unoptimised liquid-fed pulsed plasma thruster, operating at a discharge energy of 4 J. The liquid propellant feeding sub-system is shown to deliver propellant to the discharge chamber without any moving parts, and provides active and variable control of the mass flow rate. The pump can operate at a mass flow rate between 55.49 ug/s and 333.35 ug/s. Further design exploration and optimisation is needed to decrease the achievable mass bit. The wide range of mass flow rates is appropriate for a large spectrum of PPT units, and it can be altered by simply varying the applied voltage. The actively controlled flow rate may enable thrust mode selection from electrothermal to electromagnetic during flight.
A 500-shot campaigns has been run to validate the entire thruster operation. The electrostatic feeding system proved its operation by transporting a total of 95.8 mg during the 500-shot campaign. The ablated mass bit has been estimated by weighing the thruster unit before and after 500 consecutive shots. The total mass bit delivered is estimated to have been 208 ug, which may be reduced or increased through scaling and optimisation of the electrostatic pump. Out of the 208 ug mass bit, 16 ug per shot was exhausted (via ablation, evaporation, or as droplets).

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ORCID for Cristian Dobranszki: orcid.org/0000-0002-9045-4334

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