• Dual Firing
• Cluster
• Hall thruster

Hall thrusters are increasingly being used in missions that are well suited by an electric propulsion system. Large commercial satellite constellations and science missions like Psyche demonstrate their technology maturity and the interest in scaling these thrusters, which can power future missions and transportation demands. Scaling these thrusters up would cut down transit times and enable large cargo & manned missions to Mars and further out. Various approaches are adopted for scaling these thrusters, like nested and clustered Hall thrusters. Though each have their own merits, clustered thrusters can provide high scalability and redundancy at low development costs, making them an interesting choice for future high power electric propulsion systems.

In this work, the literature on the clustered Hall thruster across all power levels was reviewed, clustering effects in the plume and their relevance across various power levels were highlighted. These effects are quantified in a 5 kW class Hall thruster, first to assess their impact on the overall performance of a Hall thruster in a cluster and then to study the optimal inter thruster distance in a cluster. The neutral density in a cluster was computed using analytical models to estimate the thrust increase due to local mass reingestion, which was obtained to vary from 0.16 mN to 0.09 mN in a P5 cluster for inter thruster distance ranging from 30 to 50 cm. The increased electron mobility in the near field plume of a cluster was evaluated to generate thrust losses that are effectively negligible compared with a standalone P5 thruster. Finally, the ion focusing effect in a cluster was analyzed in a high power cluster and particle trajectories of CEX ion initiated from multiple locations and initial conditions in the plume were computed. The contribution to the thrust of ion focusing effect was observed to decrease with an increase in inter thruster distance, varying from 0.016 mN to 0.008 mN for 30-45 cm distance between thruster centrelines in a cluster.