The Effect of Accelerator Parameters on Mechanical Tuning of rf Cavities

The rf system of a proton synchrotron requires a frequency-modulated rf voltage to accelerate the particles. This paper discusses a unique method for frequency modulation of rf cavities by means of a "Loud Speaker" type of mechanical rf tuning system of the type originated by W. Schnell of CERN. A typical mechanically tuned rf system for a medium-energy high-repetition-rate particle accelerator is used to illustrate (a) the optimization of the moving portion of the tuner; (b) the control system and the response limits on the servo loop; (c) the mechanical response of the moving part and its effect on tuning accuracy.