Development of ignition unit for a liquid pulsed plasma thruster

Abstract

Solid-fed Pulsed Plasma Thrusters (PPTs) are the only mission employed devices to-date, although they suffer from low-efficiency and lifetime limiting post-ablation effects; oppositely, gas-fed PPTs offer high efficiency (~15 – 50 %) and no contamination; however, they are subject to propellant leakage issues, difficult ignition synchronisation and higher implementation costs. Liquid-fed PPTs require the sub-systems to be revisited to adapt the device to the intrinsic benefits of fluid propellants; it is suggested to use electrowetting to initiate Perfluoropolyether (PFPE) motion under the influence of electric fields. Employing a combination of dielectric materials, locally enhanced electric fields may be manipulated to decrease the ignition voltage and consequently increase efficiency. Preliminary measurements of PFPE bulk breakdown and the electrowetting-tip ignition at the liquid surface leading to reliable ignition voltages of 8.98 ± 0.86 kV are reported. The significance of PFPE motion at the cathode/vacuum interface is discussed and a vacuum breakdown mechanism relevant to the system is hypothesized, based on the MDV vacuum breakdown model.

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Identifiers

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

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