High Rotational Speeds in Vacuum

Abstract

Rotors freely suspended in high vacuum were driven to high rotational speeds by electrostatic and by electromagnetic forces. The first suspension used was a modification of the photoelectrically stabilized suspension developed in this laboratory by F. T. Holmes. Another magnetic suspension was developed which was stabilized by capacity coupling. The electrostatic drive consisted of a charged bisymmetrical blade free to rotate between quadrant plates to which were applied alternating potentials generated either by interruption of a beam of light by the rotor, by capacity pick-up, or by an external oscillator. Rotors were also driven by rotating magnetic fields. Objects suspended varied in weight from 7 g to 1200 g. The highest speed attained was 3200 r.p.s. using a 14-g rotor. A deceleration of 2.2×10−4 rev./sec.2 was measured with a 47-g rotor (moment of inertia, 103 g cm2) running at 650 r.p.s. with no applied torque.