An Displacement Transducer for a Superconducting and Electrostatic Hybrid Suspension System

A displacement transducer for a superconducting and electrostatic hybrid suspension system has been designed and fabricated in Institute of Electrical Engineering. The hybrid suspension system was designed based upon a superconducting suspension system by introducing an electrostatic suspension system (ESS). The ESS consists of eight symmetrically aligned electrodes, which have been insulated to avoid electric breakdown, and a niobium rotor in the center of the spherical cavity. How to measure the position of the spinning rotor is thus analyzed and an approach used to ensure that the rotor ground potential is given. However, insulation of the electrodes influences the displacement measurement of the bearing system, which is based on the capacitance bridge method. Then how the electrode insulation affects gap capacitances and displacement measurement is studied. To quantify this influence of electrode insulation, an enhancement factor is introduced, and the model of the displacement transducer is thus remodeled. Preliminary tests at room temperature show that displacement transducer has a measurement precision of ∼0.2 μm, with the electrodes insulated. Technical feasibility of this displacement transducer has been proved.