Mitigation of Penalties on Clustered Hall Thrusters

Hall-effect thrusters are the most common form of applied Electric Propulsion technology and are being increasingly used in SmallSat missions. Clustering Hall-effect thrusters is a developing approach used to achieve higher thruster density and redundancy on small satellite platforms, but close-proximity operation between thrusters can introduce plume-plume interactions that degrade performance. This paper presents a comprehensive study of maintaining a tight cluster of small satellites in low Earth orbit (LEO) and how intersatellite spacing influences the required station-keeping effort. We consider a leader-follower two-satellite formation subject to differential atmospheric drag perturbations and controlled by fixed-thrust (non-throttleable) Hall-effect electric propulsion. A simulation campaign is conducted to quantify key metrics, including the additional velocity change (delV) needed for formation-keeping, angular divergence of the orbit paths, propellant consumption penalties, and power/burn-time requirements, as functions of the spacing between spacecraft. Results indicate the existence of a worst-case spacing (on the order of a few centimeters for a 1U–3U CubeSat-class vehicle) that maximizes differential drag effects, leading to significantly higher delV and propellant usage compared to either very tight configurations (nearly collocated satellites) or widely spaced formations. We also analyze the sensitivity of formation-maintenance requirements to atmospheric density variations (e.g., due to solar activity) and discuss the practical implications for mission design. The study concludes with recommendations for optimal spacing to minimize fuel/power costs and outlines future work on advanced control strategies and multi-satellite cluster configurations.

Keywords: Hall-effect propulsion, CubeSat formation control, electrostatic plume coupling, LEO dynamics