Design and testing of a water-fueled low-power magnetically shielded Hall thruster
Engineering Design, Machine Elements, Product Development
Final Report Abstract
Hall thrusters are a promising technology for small and microsatellites that generate thrust by electrostatically accelerating ions. They offer higher fuel efficiency and simpler construction compared to chemical propulsion systems. Xenon, the standard propellant for electric thrusters, has ideal properties such as high atomic mass, good ionization efficiency, and chemical inertness. However, it is expensive and requires high-pressure storage tanks. The search for alternative propellants is essential to make electric propulsion accessible to smaller research institutions with limited budgets. Water is an attractive alternative: it is inexpensive, non-toxic, widely available, and can be stored as a liquid in simple tanks. However, water is harder to ionize, produces lower thrust due to its lower atomic mass, can dissociate into undesired particle species, and tends to overheat the thruster due to higher power losses. This project developed an innovative Hall thruster design for use with water to ensure thermal stability and reduce erosion. Permanent magnets replaced conventional electromagnets, the discharge channel design was improved, and regenerative cooling methods were explored. The thruster was successfully tested with both xenon and water. Using xenon, it achieved thrust, efficiency, and specific impulse (Isp) comparable to other thrusters in its size and power class. With water, performance was slightly lower, likely due to modifications in the magnetic field configuration. An endurance test revealed minimal erosion of the discharge channel after 30 hours of xenon operation. However, significant erosion was observed after just 20 hours of operation with water. Further investigations are needed to determine whether the design was suboptimally implemented or whether the anti-erosion measures are inherently less effective with water. This project represents a significant milestone: the world’s first water-based Hall thruster capable of continuous operation. This technology could provide an affordable and sustainable solution for small satellite propulsion, further democratizing access to space.
Publications
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Design, performance, and preliminary erosion evaluation of a 50 W–200 W water-fueled Hall thruster with permanent magnets. Acta Astronautica, 232, 693-705.
Gondol, Norman; Shirasu, Kento; Yoshida, Hayato & Koizumi, Hiroyuki
