An upgrade cryomodule is being developed for CEBAF at Jefferson Lab. The high-gradient, low-current operation of the superconducting cavities puts stringent requirements on the accuracy of the frequency tuner: a resolution of 1Hz over a range of 400 kHz . We have developed and tested such a tuner; it consists of a stepper-motor-driven coarse tuner, operating in series with a piezo-actuator-driven fine tuner. Tuner test procedures and results are summarized, including frequency resolution, range, and li nearity (i.e. frequency vs. tuner position), as well as microphonic effects resulting from tuner operation.

This work was supported by the U.S. DOE Contract No. DE-AC05-84ER40150.

Authors: M. Stirbet, I.E. Campisi, G.K. Davis, M. Drury, C. Grenoble, G. Myneni, T. Powers, K.M. Wilson

Abstract submitted to PAC 2001, Chicago, IL, June 18-24, 2001

Updated July 27, 2001

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