Deflagration Thruster for Air-Breathing Electric Propulsion in Very Low Earth Orbit

This study establishes the performance requirements for an air-breathing electric propulsion device to operate in very low Earth orbit (<450 km). We demonstrate that existing electric propulsion architectures, including electrostatic thrusters, fail to generate enough thrust while operating on flow rates of air that can be harvested in orbit. Instead, we develop and characterize a type of electromagnetic pulsed thruster that operates in a magneto-deflagration mode (i.e., forms an expansion wave during the acceleration process) that becomes more efficient as less propellant is used. We show this mode of operation can generate specific impulses up to 104 s, thrust per power >2 mN/kW, thrust densities >100 mN/m2, and thrust efficiencies up to 10% while consuming <100μg of air per discharge. We map these performance metrics on a candidate spacecraft to show the deflagration thruster can enable fully air-breathing drag compensation at altitudes ranging from ∼200 km to 350 km depending on its geometry and is extendable to other altitudes if stored propellant is utilized.