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The purpose of this study is to investigate the use of RF heating to enhance the efficiency of a single stage Hall Effect Thruster operating on the products of water electrolysis: oxygen for the anode and hydrogen for the cathode. This research builds of the heritage of the Water ElecTrolysis Hall Effect Thruster (WET-HET) which has been recently developed and successfully demonstrated within the Imperial Plasma Propulsion Laboratory. Here, we propose to enhance its efficiency using auxiliary RF heating, with the aim of increasing the thrust efficiency to levels comparable to conventional Xenon fuelled Hall Effect Thrusters. This accomplishment would be a key step toward commercial and scientific exploitation of water as a propellant for electric propulsion applications. We anticipate that the key research challenge will be obtaining an overall improvement to the thrust efficiency considering the additional power supplied for the RF heating and any other possible loss mechanisms. On one hand, it is expected that the ionization rate will be substantially improved thanks to the electron energy absorption, which in turn will increase the propellant utilization efficiency, lower the anode voltage at a given power and improve the beam divergence. On the other hand, the RF heating itself will impose additional energy requirements on the system, as well as increasing the cost and complexity of the design. The final outcome of this research will be the experimental measurements of the thruster performance that can be used to quantitatively assess the trade-offs highlighted above and inform future developments of this technology. An exciting prospect for future exploitation is that this technology could ultimately lead to a radical innovation of the satellite architecture: a water fuelled multi-modal chemical + electric propulsion system cleverly augmented by the RF generator within the communications subsystem.
