Developing and testing a direct drive intended for special vacuum application

New electromagnetic applications and storage devices demand for knowledge of magnetic domains of used materials. These can be investigated by examination of a diverted X-ray beam. For the diversion a rotating condenser is used. The paper describes the development of a drive for this rotating system. During development some requirements resulting from the use in vacuum have to be considered. The whole system which run without vibrations and speed ripples benefits tremendously from a direct synchronous drive with permanent magnetic excitation. The rotation is evoked by combination of the rotating magnets mounted on the condenser and the stator mounted outside a steel tube surrounding the vacuum. At the end of the paper a method for determination of speed ripples is shown