RF Accelerating Cavities for AGS Conversion

The RF accelerating cavities at the Brookhaven AGS are of the balanced, coaxial type, filled with ferrite to allow permeability tuning. The basic limitation in such a cavity is heat dissipation in the ferrite. It is the purpose of this paper to study the behavior of such a cavity as dc bias is applied to the ferrite. It will be shown that RF flux density is inversely proportional to radius only at zero bias; as the bias current increases, the flux density approaches a nearly uniform distribution, resulting in nearly uniform heating. The results are applied to the problem of increasing the operating voltage of the present AGS cavities as well as to the design of a new cavity for the AGS conversion project.