Preliminary experimental characterization results of a freely expanding 10 N bi-propellant thruster plume

Abstract

Sensitive spacecraft components are prone to degradation when exposed to satellite thruster plume components. This work focusses on the experimental and numerical characterization of a freely expanding 10 N MMH/MON bi-propellant thruster plume in order to estimate its contamination potential, which prospectively allows for enhanced mitigation strategies of the aforementioned spacecraft deterioration. An extensive plume characterization by pitot probe, heat flux and mass spectrometry measurements is complemented by high-speed imaging of the nozzle exit area and spacecraft material exposure, followed by an in-depth chemical analysis. Furthermore, two CQCMs collected data on exhaust gases of the freely expanding plume deposited at 70 K under angles up to 90° off-axis. Preliminary findings of this on-going study indicate that FORPs (fuel-oxidizer reaction products) were collected on witness materials which are currently being chemically characterized. The characterization of the composition and distribution of burnt and unburnt propellant enables to understand and minimize potential spacecraft contamination processes.