Running
URA Thrusters and Imperial College London are developing a dual-mode chemical-electric propulsion architecture. The architecture’s electric propulsion subassembly features a hydrogen fueled cathode and a water fueled Hall effect thruster (AQUAHET). To further progress on this development, we propose here to focus on investigating the use of water for Hall Effect thrusters (HETs). Xenon currently dominates the market as the de-facto standard propellant for HETs. Its ongoing use however is constrained fundamentally by its high cost, scarcity, and volatile pricing. As research to date on alternative propellants for HETs has focused on elements such as krypton, iodine, and bismuth, our novel water development will push the state-of-the-art. The key challenge for this work will be obtaining competitive thrust efficiency despite the presence of the added energy loss mechanisms that can be expected in a water plasma. In these plasmas, loss mechanisms including non-ionizing dissociation and molecular excitation of rotational-vibrational states result in overall higher ionization costs. Our aim is to investigate the extent to which the design of a Hall Effect thruster can be optimized for use with water. Research work will build on the lessons learnt from the design and test of an oxygen based HET at Imperial College. Encouraging preliminary results from water plasma simulations conducted using an in house Particle-in-Cell code called PlasmaSim predict higher specific impulse and efficiency levels compared to oxygen. The following performance targets for the AQUAHET were established using these results: - Specific impulse: 5400 s - Thrust: 30 mN - Discharge power: 1.5 kW - Anode thrust efficiency: 45 % Using these simulations as a starting point we propose to design and build a laboratory prototype thruster. The thruster hardware, along with an extensive set of performance and plasma characterization experimental measurements, will constitute the final outcome of the project.
