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An air-blower with active magnetic bearings could improve working efficiency and reduce energy consumption by avoiding contact between the rotor shaft and the stator part. The structure and prototype of a magnetically suspended air-blower are herein introduced, and the force models of active magnetic bearings developed. Furthermore, the dynamic models of a rotor shaft with unbalance terms were established to investigate the vibration characteristics of the magnetically suspended air-blower. The vibration characteristics of the rotor shaft with unbalance terms were analyzed, and the complex-field cross-feedback control was designed to suppress the vibration amplitude. Finally, experiments were conducted to verify the theoretical models, and the results indicated that the vibration amplitude of the rotor shaft with unbalance terms could be intensified by the rotating frequency, and the nutation vibration was reduced by 50% through increasing the high-frequency nutation coefficient of the complex-field cross-feedback control model. The results indicated that the vibration analysis of the rotor shaft was meaningful to the design and control of the magnetically suspended air-blower.

A planar Langmuir probe, which can be used for both ion electric propulsion beam characteristics measurement and plasma diagnosis, was developed and applied to plume measurement and diagnosis experiments of an 8 cm Kaufman ion thruster to address the growing demand for miniaturized ion thruster plume measurement and diagnosis. The experimental results show that the plume area exhibits good symmetry along the central axis, and the beam dispersion angle of the 8 cm ion thruster is approximately 22.7°. The radial distributions of the floating potential, plasma space potential and ion density are similar, showing a high distribution in the middle and a relatively low distribution at the two ends. The miniaturized ion thruster plume measurement and diagnosis system is not only easy to manipulate, but also fast and efficient for plasma plume measurement and diagnosis, which provides more complete data support for analyzing the working state of the miniaturized ion thrusters and optimizing the design of the thruster structure.

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