Folded Ferrite Loaded Cavities for Impedance Matching in the AGS

The AGS conversion requires twice the accelerating volts/turn and driving amplifiers removed from the ring to a central building. The accelerating cavities must be tuned over a frequency range of 2.5 MHz to 4.5 MHz. In addition the number of accelerating positions will be reduced from twelve to eight. These specifications combine to place severe restrictions on the accelerating cavity structure. To minimize power losses in the cavity it is necessary that more ferrite be added. A method of folding the cavities in the radial direction yields a structure which not only raises the cavity impedance, but also enables matching to the input line without using a broad band transformer. A further desirable feature of the structure is the ability to place four gaps, rather than two, in each accelerating straight section thus halving the voltage per gap and halving the voltage on the input lines. A sample computation has been made using currently available ferrite in sizes essentially the same as have been used at the AGS and PPA. The results look favorable and additional ferrites are being investigated to find higher ¿Qf values.