• Manufactured prototype
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The development, manufacture, and testing of a neutraliser for XSEPT, the university gridded ion thruster project
Group Members
Joseph Edwards, Alessandro Arno, Marcus Collier-Wright, Richard Jones, Sam Reeve, Maria Sevilla, Peter Turner, Wojciech Zakrzewski
Supervisors
Dr. Angelo Grubisic, Dr. Min K Kim
Supporters
Kepston Ltd, David Hoffman
Electric propulsion for spacecraft offers greater efficiency and requires less propellant than conventional chemical rocket thrusters. Electric thrusters have a wide range of applications, such as long-duration orbital manoeuvres, interplanetary transfers, and satellite station keeping. Gridded ion thrusters produce thrust by ionising propellant and using electric fields to accelerate the ions. However, they require an additional component, a neutraliser, to prevent the build-up of charge on the thruster.

The aim of this project was to develop, manufacture, and test a neutraliser for XSEPT, the gridded ion thruster project under development by the University of Southampton. Secondary objectives were to use additive manufacturing to produce components where possible, and to test various designs of the neutraliser components.

Both the thruster and the neutraliser operate using an innovative method known as Electron Cyclotron Resonance (ECR). This uses a tailored combination of microwaves and powerful magnetic fields to ionise the propellant. ECR has the potential to greatly increase the operational lifetime compared to traditional neutralisation methods. The project is the first European thruster to make use of ECR.

The design process involved using COMSOL Multiphysics to model the magnetic and electric fields in the neutraliser, Python scripts to characterise and predict the overall performance of the neutraliser, and ANSYS to perform thermal and structural analysis.

The neutraliser components have been entirely manufactured by the university Engineering Design and Manufacturing Centre, with heat-treatment process’ undertaken externally by Kepston Ltd. Several minor manufacturing tasks were performed by members of the GDP team.
The Discharge Chamber is critical for containing the plasma and facilitating ion recombination
The Neutraliser assembly, mounted to the test rig prior to vacuum chamber testing
The Faraday Cage Base creates the framework to assemble the complete Faraday Cage
The Reservoir Plate supplies Argon propellant to the Neutraliser through four nozzles, spaced at 90 degree intervals
Exploded view of the Neutraliser and its components
The ignition of the Neutraliser demonstrates the successful modelling, simulation and design conducted throughout the course of the project. This image shows the ignited plasma within the discharge chamber, observed through the orifice plate