Rotational feedthrough using an ultrasonic motor and its performance in ultra high vacuum conditions

Ultrasonic motor is one of the promising actuators that are utilized in ultra-high vacuum (UHV) conditions. The authors have proposed a rotational feedthrough for UHV using a mode-rotational type ultrasonic motor. This rotational feedthrough is distinguished by its-arrangement of driving parts. The piezoelectric ceramics and wiring parts were arranged outside the vacuum chamber because they can be source of outgases. Previously the authors have just proposed this idea and reported on the successful operation in vacuum, although the output torque and duration of operation were insufficient for such applications as positioning tables. In this study, the stator transducer was redesigned for larger output torque and stator-rotor interface materials were modified from combination of metal-ceramic to metal-plastic. As a result, output torque and duration of operation were improved by factors of 4 and 20, respectively; 22mNm and 27h. In addition, baking treatment was carried out and an UHV of 3 x 10(-7) Pa was achieved. (C) 2003 Elsevier Science Ltd. All rights reserved.