Background Pressure Effect on a Novel ECR Magnetic Nozzle Thruster

Low backing pressures are essential to accurately measure the performance of electric plasma thrusters. Too high backing pressures can increase the performance of Ion and Hall thrusters, invalidating experimental results. Conversely, the performance of Electron Cyclotron Resonance (ECR) Magnetic Nozzle Thrusters is reduced by high backing pressures.

A linear increase in thrust with a logarithmic decrease in backing pressure has been previously observed. This relationship has been experimentally verified and measured in the Surrey Space Centre’s large vacuum chamber with a novel ECR Thruster developed at the University of Surrey. Plume measurements will be taken via Optical Emission Spectroscopy as well as Faraday and Langmuir probes to determine facility pressure effects on electron temperature and plume divergence. However, with the thruster running, Surrey’s large vacuum chamber can only achieve a backing pressure of 6E-6 mbar. To test backing pressure effects at lower pressures the thruster will be tested in the University of Southampton’s large vacuum chamber. As vacuum chamber size has also been known to affect the performance of ECR Magnetic Nozzle Thrusters, performance will also be compared between the two chambers.