Study on Noncontact Driving of Disk by Piezoelectric Transducer under Cryogenic Condition

A cryogenic environment has been used widely for scientific measurements and there is a demand for small actuator for the operation of sample objects. Some piezoelectric actuators including ultrasonic motors have been proposed and evaluated under cryogenic condition. Generally, those actuators use frictional contact driving between a rotor and a stator transducer. Under the cryogenic temperature, the damage due to low temperature brittleness of contact surfaces becomes an important problem. In this study, a transducer to achieve noncontact driving under cryogenic condition has been proposed. A bolt clamped type transducer was designed and fabricated to levitate an object under a cryogenic environment. The basic performance of the fabricated transducer was evaluated. The transducer was installed in a gas cell filled with helium and the cell was in a refrigerator. The levitation of the disk has been observed in the refrigerator at 4.3 K. The experimental results show the almost similar relation to theoretical estimation.