Performance Characterization of an ECR Magnetic Nozzle Thruster Using Atmospheric Propellant

The performance of an electron cyclotron resonance (ECR) magnetic nozzle thruster operating on air is evaluated. This investigation is motivated by the possibility of using air-breathing plasma propulsion to perform drag compensation for spacecraft in very low earth orbit.  ECR magnetic nozzles in principle are capable of operating on a wide variety of propellants.  However, while there are experimental or analytical results for ECR magnetic nozzles operating on water vapor, argon, and xenon, little comparable information exists for such a thruster running on air.  This work presents the results of a study characterizing the performance and efficiency of an ECR magnetic nozzle operating on air.  Thrust and specific impulse are assessed using a pendulum thrust stand, and measurements performed with a diagnostic probe suite are used to estimate key contributions to the thruster efficiency, e.g. divergence and mass utilization.  These results are interpreted in the context of a 0D power balance model.  Potential strategies for improving performance are also discussed including the use of a two-frequency optimization scheme recently devised by Wachs [1].

[1] B. Wachs and B. Jorns, IEPC-2019-219 (2019)