EM Topology Stability and Active Field Governance for High Power Hall Thrusters

Abstract

The in-flight checkout of the Psyche spacecraft's SPT-140 Hall thrusters (Oh et al., Journal of Spacecraft and Rockets, 2026) documents five classes of transient and quasi-steady behaviour: burn-in thrust decay, extended mode-hopping, sensitivity to magnet-current settings, ground-to-space performance differences, and thrust variability during calibration. This Technical Comment reinterprets these observations within a unified electromagnetic-topology framework, demonstrating that each behaviour is a manifestation of one of four underlying EM-topology mechanisms, sheath evolution, magnetic-topology drift, ionisation-driven oscillations, and environment-dependent discharge equilibria, rather than an isolated anomaly. The analysis establishes that these instabilities are structural features of passive-topology Hall-thruster architectures and will become increasingly consequential as mission lifetimes and power levels grow. The Psyche dataset is further examined for its relevance to active electromagnetic field-governance research. A one-to-one correspondence is identified between the five observed behaviours and the stabilisation functions of the Rotating Electromagnetic Nozzle (REMN), an external field-governance architecture designed to suppress mode transitions, damp harmonics, lock B-field topology, and compensate for environmental boundary-condition changes in real time. The Psyche checkout data is presented as a valuable real-flight reference for evaluating next-generation active field-governance approaches in high-power electric propulsion.