A "Monochromatic" Radio Frequency Accelerator Cavity

In circular accelerators and storage rings it is important that any device placed in the beam line be relatively free of spurious resonances. Accelerating RF cavities inherently have an infinite number of spurious modes. The cavity to be described in this paper makes use of certain geometric construction configurations that eliminate all the spurious modes. A cavity was constructed with an accelerating TMolo mode of 90 MHz. Measurements showed that the TMolo mode was essentially unchanged from a conventional cavity but all modes up to 3 GHz were either completely eliminated or reduced by at least 30 db.