Fast Camera Analysis of Plasma Instabilities in Hall Effect Thrusters Using a POD Method under Different Operating Regimes

Victor Désangles,Simon Vincent,Sergey Shcherbanev,Anne Bourdon,Pascal Chabert,Clarence Deltel,Thomas Charoy,Pablo Richard,Noé Clément

doi:10.3390/atmos11050518

Abstract

Even after half a century of development, many phenomena in Hall Effect Thrusters are still not well-understood. While numerical studies are now widely used to study this highly non-linear system, experimental diagnostics are needed to validate their results and identify specific oscillations. By varying the cathode heating current, its emissivity is efficiently controlled and a transition between two functioning regimes of a low power thruster is observed. This transition implies a modification of the axial electric field and of the plasma plume shape. High-speed camera imaging is performed and the data are analysed using a Proper Orthogonal Decomposition method to isolate the different types of plasma fluctuations occurring simultaneously. The low-frequency breathing mode is observed, along with higher frequency rotating modes that can be associated to rotating spokes or gradient-induced instabilities. These rotating modes are observed while propagating outside the thruster channel. The reduction of the cathode emissivity beyond the transition comes along with a disappearance of the breathing mode, which could improve the thruster performance and stability.

Highlights

IntroductionThe number of satellites orbiting around Earth has grown exponentially.For various applications (orbital station-keeping, collision avoidance, etc.), a propulsion system is needed aboard these satellites
In the last decade, the number of satellites orbiting around Earth has grown exponentially.For various applications, a propulsion system is needed aboard these satellites
The magnetic field amplitude is usually studied as the main parameter for transitions between Hall-Effect Thrusters (HET) functioning regime [38,39,40,41]

Summary

Introduction

The number of satellites orbiting around Earth has grown exponentially.For various applications (orbital station-keeping, collision avoidance, etc.), a propulsion system is needed aboard these satellites. Electric propulsion appears to be the best option and ion-gridded thrusters along with Hall-Effect Thrusters (HET) are routinely used [1,2] The latter are known from the 1960s and have been successfully used in space (for example, the Safran PPS-1350 on the ESA SMART-1 mission to the moon, in 2003), but, despite extensive studies [3,4,5], the physics of these thrusters is still not well-understood. In these devices, a neutral gas, often Xenon, is injected through an anode ring located at the back of an annular discharge channel. The gas is ionised by electrons emitted by a cathode located at the Atmosphere 2020, 11, 518; doi:10.3390/atmos11050518 www.mdpi.com/journal/atmosphere

Objectives

Methods

Results

Conclusion