Design of a Gas Spin-Up System for an Electrostatically Supported Cryogenic Gyroscope

Abstract

This paper describes a method of spinning an electrostatically supported cryogenic gyroscope to speeds in excess of 200 cps. The gyroscope has been designed as part of the preliminary work on a satellite experiment to test general relativity originally suggested by Schiff [¹]. The gyro, shown schematically in Fig. 1, consists of a 1.5-in.-diameter quartz ball with a homogeneity of 1 part in 10⁵, which is coated with a thin film of superconducting niobium and supported in a vacuum by three orthogonal pairs of electrodes.† The spacing between the electrodes and the ball is approximately 0.0038 cm, and the support voltage in the earth’s gravitational field is approximately 500 V rms. The use of a superconducting ball is dictated by the readout system of the gyroscope, which locates the axis by measuring the direction of the magnetic field associated with the “London moment” of a spinning superconductor [²]. An operating speed approaching 200 cps is required to give adequate drift performance and readout sensitivity. The operating speed is made somewhat lower than that in other types of precision gyroscopes in order to limit the centrifugal distortion of the ball.

Supported by National Aeronautics and Space Administration under Grant NsG-582.