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Design and evaluation of ultrasonic motor located in cryogenic temperature environments

An ultrasonic motor driven in the cryogenic temperature environment has been designed, fabricated and evaluated. This motor has bolt-clamped Langevin-type transducer. The maximum diameter and length of the motor are 22 mm and 30.5 mm. The aim of this paper is to evaluate the specification of this motor at cryogenic temperature. By estimating the thermal stress of the transducer and adjusting the contact pre-load between the rotor and the transducer, we have succeeded in driving the motor into cryogenic helium gas. The rotation speed of the motor was evaluated at cryogenic temperature. The rotation speed was 65.4 rpm at 4.5 K.