Additive Manufacturing of Hall Thruster Magnetic Circuits

Hall thrusters are one of the most widely used electric propulsion systems, primarily due to their relatively high thrust-to-power ratio and simple architecture. Despite the high technology readiness level reached in recent years, there is still significant room for improvements in performance, structural design and thermal management. In this sense, a crucial role could be played by the additive manufacturing (AM) of magnetic circuits. This component plays a fundamental role in the functioning of the thruster, as the magnetic field topology and intensity are fundamental variables for controlling discharge stability, ion acceleration, and channel erosion phenomena. Additionally, the magnetic circuit serves as the support structure for the majority of the other thruster components. The freedom in design and the possibilities to reduce mass, consolidate components, and optimize thermal management offered by AM open the doors to the creation of more efficient and robust thrusters. Moreover, the rapid prototyping capability and reduced production costs allow for quick testing of new concepts, accelerating scientific progress in this field. This article aims to present the progress made in developing an additive manufacturing production procedure for creating magnetic circuits for Hall thrusters at the University of Pisa. The method developed is based on material extrusion additive manufacturing of polymeric filaments highly loaded with metal powders. This technique allows for the printing of soft ferromagnetic components using a conventional desktop printer, followed by debinding and sintering treatments to produce fully metallic parts. The article presents the results obtained with two soft iron filament feedstock: the first commercially available, and the second developed in collaboration with Nadir Srl as an upgrade of the former. The magnetic properties of the two materials subjected to different heat treatments are reported. The effectiveness of the technique is demonstrated through the realization of the magnetic circuit of a low-power thruster, whose design process is described in detail. The developed production procedure has shown the research group’s