Speaker
Description
In the future, Air-Breathing Electric Propulsion (RAM-EP) systems may enable low-altitude missions over long lifetimes. The European consortium “AETHER” is currently designing a RAM-EP prototype for ground testing. In the context of this project, an experimental effort has been conducted to characterize the Particle Flow Generator (PFG), which is responsible for providing the RAM-EP system with a high-speed flow representative of actual in-orbit operation. In a first preliminary test campaign, a Sitael 5kW-class Hall-Effect Thruster has been operated with xenon, air, and in a mixed-propellant mode.
Optical emission spectroscopy is a widely used diagnostic method for low-temperature plasmas due to the affordability and simplicity of its experimental setup. The diagnostic relies on an intensity-calibrated spectroscopy system to record the emission spectra from the UV to the near-IR region over a range of wavelengths. The emission spectra are typically interpreted using a model that accounts for transitions between the internal energy levels of the different species of the flow. As the radiation signature of the plasma depends on the species level distribution, spectroscopic measurements allow the extraction of the plasma electron temperature and electron density through the comparison of synthetic and experimental emission spectra.
We compute electron temperatures along the PFG plume axis based on the described approach. The same procedure is applied to obtain radially resolved profiles. We analyze the impact of Xe on the radiative signature of air, and we discuss the possibility of using Xe as trace species to obtain air plasma parameters in a mixed-propellant mode. Finally, we employ a collisional-radiative quasi-1D expansion model to infer plasma conditions at the PFG exit.
Summary
In the future, Air-Breathing Electric Propulsion (RAM-EP) systems may enable low-altitude missions over long lifetimes. The European consortium “AETHER” is currently designing a RAM-EP prototype for ground testing. In the context of this project, an experimental effort has been conducted to characterize the Particle Flow Generator (PFG), which is responsible for providing the RAM-EP system with a high-speed flow representative of actual in-orbit operation. In a first preliminary test campaign, a Sitael 5kW-class Hall-Effect Thruster has been operated with xenon, air, and in a mixed-propellant mode. We present results obtained from optical emission spectroscopy. In particular, we compute electron temperatures in the PFG plume, and we discuss the possibility of using Xe as trace species to obtain air plasma parameters in a mixed-propellant mode. Finally, we employ a collisional-radiative quasi-1D expansion model to infer plasma conditions at the PFG exit.
