一种可加载直流偏压调节等离子体均匀度的电子回旋共振离子推力器设计和实验

Electron cyclotron resonance (ECR) ion thruster faces significant challenges under low-power and low-mass-flow-rate conditions. The strong magnetic confinement required for ECR discharge often leads to severe plasma non-uniformity within the discharge chamber, which significantly limits thrust density and shortens grid service life due to poor beam focusing. To address these issues, this paper proposes an active control method by applying a direct current (DC) bias to the side wall of the thruster. A 50 mm diameter cylindrical cusp ECR ion thruster was designed and integrated with a side-wall electrode and a central rod electrode. By applying a DC bias of 0-150 V to the side wall, a radial electric field pointing towards the center of the discharge chamber was established to drive ions across the magnetic field lines. The effects of the DC bias on the current characteristics, ion beam parameters, and radial plasma distribution were systematically investigated, and a rod-cylinder electrode theoretical model was established to elucidate the underlying physical mechanisms. The experimental results demonstrate that the proposed method effectively modulates the plasma transport and focusing state. Specifically, under the operating condition of 0.6 sccm (1 sccm = 1 mL/min @0°C, 1.013× 10⁵ Pa) xenon flow and 14.9 W microwave power, the plasma uniformity was significantly improved from 0.39 to 0.75 by adjusting the side-wall voltage to 90 V. When the side-wall voltage reached 150 V, the beam divergence half-angle was reduced from 14.77° to 7.31°. Most notably, both thrust and specific impulse were enhanced by approximately 65% under the optimal operating conditions compared to the unbiased case. The analysis of current characteristics confirms that the discharge transitions from a magnetic confinement-dominated mode to an electric field-driven transport mode, effectively filling the central low-density zone. This study validates the feasibility of using electric-field-assisted method to flexibly optimize the comprehensive performance of ECR thrusters without altering their physical structures, providing a new strategy for the design of micropropulsion systems.