Experimental demonstration of a second generation water electrolysis Hall Effect Thruster (AQUAHET)

A second generation water electrolysis Hall Effect Thruster ( AQUAHET ) is presented and characterised using the by-products of water electrolysis from pressurised cylinders: oxygen for the anode (thruster) and hydrogen for the cathode. This new device builds upon a first generation water electrolysis Hall Effect Thruster ( WET-HET ), featuring an increased channel mean diameter of 40 mm compared to 20 mm for the WET-HET , and also a reduction of the non-radial magnetic field line components close to the thruster exit plane. First, the most optimum operating points for the AQUAHET in terms of magnet current and anode mass flow are determined. This device allows for changes of the channel width from 4 mm to 5 mm, and both configurations are tested. As the combined use of oxygen and hydrogen require the implementation of stringent health and safety procedures, krypton is used as the cathode propellant in these initial analyses to simplify the testing procedures used. The results showed that a 5 mm channel width is more beneficial in terms of anode thrust efficiency. The best operating point was obtained at an anode mass flow of 1.7 mg/s and a Gaussian radial magnetic flux density peaking at B ≈ 500 G. When using the by-products of water electrolysis from pressurised bottles, no discernible differences are seen when changing the hydrogen-to-oxygen ratio ( Φ ), in alignment with previous investigations. The change of cathode propellant from krypton to hydrogen showed an approximate 10% reduction in anode thrust efficiency. On average, the second generation water electrolysis Hall Effect Thruster ( AQUAHET ) demonstrates a 20% higher performance in terms of anode thrust efficiency compared to the first generation ( WET-HET ). The best performance using oxygen-krypton was achieved at the maximum discharge power tested ( P d = 3200 ± 1 W) resulting in a thrust of T = 51 . 0 ± 0 . 5 mN, an anode specific impulse of I s p = 3118 ± 32 s, a Thrust-To-Power-Ratio of T T P R = 15 . 9 ± 0 . 5 mN/kW, an anode thrust efficiency of η t r = 24 . 4 ± 0 . 5 %, and a total efficiency of η t o t = 16 . 3 ± 0 . 5 %. Finally, the oxygen-hydrogen experimentation at P d = 1168 ± 1 W, yielded a performance of T = 19 . 9 ± 0 . 4 mN, I s p = 1217 ± 25 s, T T P R = 17 . 0 ± 0 . 4 mN/kW, η t r = 10 . 2 ± 0 . 4 %, and η t o t = 7 . 4 ± 0 . 5 %. • Experimental demonstration of a second-generation water electrolysis HET. • AQUAHET utilises oxygen and hydrogen from water electrolysis for propulsion. • Improved efficiency with adjustable discharge channel widths of 4 mm and 5 mm. • Measurements up to 3.2 kW power with 20% higher anode efficiency than WET-HET. • Addressed hardware oxidation challenges and proposed mitigation strategies.