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 to 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.