Feasibility verification of microwave-DC hybrid discharged cusped field thruster fed atmospheric propellant

Atmospheric-breathing electric propulsion (ABEP) is a pivotal technology for enabling long-term spacecraft operation in very-low Earth orbit (VLEO), holding strategic significance for contesting very low orbital dominance, substantially reducing satellite launch costs, and enhancing mission performance. This paper utilizes a microwave-DC hybrid discharged cusped field thruster (CFT) design for potential ABEP applications in VLEO and investigates its atmospheric propellant discharge feasibility through experiment. Comparative studies using xenon and air propellants were conducted to evaluate the thruster's low-pressure discharge capability and fundamental performance. Faraday probe and retarding potential analyser (RPA) measurements were employed for plume characterization, while indirect calculation methods derived thruster performance parameters including thrust and specific impulse. The results demonstrate that the microwave-DC hybrid discharged CFT sustains stable discharge across different supply conditions. At the lowest tested supply boundary, discharge dominated by microwave electron cyclotron resonance (ECR) is maintained at 0.3sccm/0.015Pa, achieving a maximum specific impulse of approximately 2700 s. At the highest tested supply parameters, discharge dominated by DC is sustained at 15sccm/0.75Pa, achieving a maximum specific impulse of about 800s.