Fast ferrite tuner for the BNL synchrotron light source

A new type of ferrite tuner has been tested at the Brookhaven National Laboratory (BNL). The ferrite tuner uses garnet slabs partially filling a stripline. One of the important features of the tuner is that the ferrite is perpendicularly biased for operation above ferromagnetic resonance, thus reducing the magnetic losses. A unique design was adopted to achieve efficient cooling. The principle of operation of the tuner as well as preliminary results on tuning a 52 MHz cavity are reported. Optimized conditions under linear tunability of 80 kHz was demonstrated. The tuner´s losses and its effect on higher-order modes in the cavity are discussed.<>