Air-Breathing Electric Propulsion Developments at NewOrbit Space

The AURA Air-Breathing Electric Propulsion System under development at NewOrbit Space has the goal for sustained operation at Ultra-low Earth orbits for Earth observation and telecommunication applications. The performance of the engineering model of the thruster assembly of this system is presented, which comprises a radio frequency Gridded Ion Engine, a radio frequency neutralising cathode and the associated radio frequency generators while operating under a 50:50 mixture of oxygen and nitrogen, and while operating under xenon. Direct thrust measurements are performed using a hanging pendulum thrust balance to measure the thrust correction factor required for accurate indirect thrust measurements. The cathode is operated on mass flow rates of 0.4 sccm O ₂  + 0.4 sccm N ₂ at powers of 90 W, and on mass flow rates of 0.15 sccm xenon at powers of 25 W. The thruster was operated on a 1:1 ratio of O ₂ :N ₂ by volume over combined mass flow rates of 5.8–14 sccm at RF input powers ranging from 60–250 W, and on xenon mass flow rates of 2-5.5 sccm and RF input powers of 25–100 W. Direct thrust measurements are found to agree with indirect measurements for thrust correction factors of 0.97 ± 0.02 for xenon, and 0.85–0.92 for O ₂ /N ₂ mixtures. For O ₂ /N ₂ mixtures, a thrust of 2.6–12.8 mN is measured and a specific impulse of up to 6503 s. For xenon, a thrust of 4.4–14.4 mN is measured and a specific impulse of up to 4423 s. The thruster assembly has now passed vibration tests and is currently being integrated into engineering model units of the remaining AURA subsystems.