| 摘要 |
<p>An ultrasonic drive which can be made in the form of packets of ultrasonic actuators, each of which, or each pair of which has a driven element, and the packets arranged so that the frictional contact and place of connection of each friction element with a piezoelectric resonance element is screened from direct or secondary alpha, beta, gamma, or neutron radiation by the driven elements of the packets of actuators themselves. In addition, the friction element of each actuator can be made wholly or partially from a material that absorbs or attenuates alpha, beta, gamma or neutron radiation, such as aluminium oxide, zirconium oxide with the addition of tungsten or tungsten carbide or tungsten or its alloys, lead or its alloys or cermets containing these materials. An ultrasonic drive achieve an increase in force, speed, reliability and durability of drives working in strong radiation fields and to increase the drive lifetime and sphere of application. The proposed ultrasonic drive is intended for use as a driver of moving parts working in fields of strong direct, secondary and reflected alpha, beta, gamma or neutron radiation, such as that found in particle accelerators, medical irradiating apparatus, in open space or other similar locations where there is a strong radiation field present. A specific example where such an ultrasonic drive may be applicable is as the drive system of the leaves of a multi-leaf collimator which provides conformal shaping of radiotherapy treatment beams to tumours. An ultrasonic drive with the above features, it is possible to achieve an increase of the reliability of an ultrasonic drive operating in the field of strong radiation. Increased reliability and increased service life makes the proposed drive suitable for service in medical devices that produce intense alpha, beta, gamma, and/or neutron radiation but also extends the field of application of ultrasonic drives to other similar environments.</p> |
