A Resonantly Coupled, Ferrite-Tuned Buncher-Cavity System for the Los Alamos Proton Storage Ring
Resonantly coupled buncher and ferrite-loaded tuning cavities at 503.125 MHz are separately optimized to provide fast tracking of time-dependent beam current changes in the Los Alamos Proton Storage Ring (PSR) while maximizing radio-frequency (rf) stability and efficiency.
Perpendicular biased ferrite-tuned cavities
For varying the frequency of accelerating cavities in rapid-cycling RF systems for synchrotrons, perpendicular biased yttrium garnet ferrites have gained popularity over the conventional parallel biased NiZn ferrites. An important milestone in fast cycling perpendicular biased ferrite tuners was reached at TRIUMF in the spring of 1991. To the best of our knowledge this is the first time that anyone has operated a fast AC perpendicular biased yttrium garnet ferrite tuner over such a large frequency swing at high RF power levels. A similar design is now being developed at SSCL for the Low Energy Booster. This paper presents a brief history of the development of perpendicular biased ferrite tuners, a comparison of the two biasing; methods, magnetic field theory of perpendicular biasing, and the problem of eddy currents produced by the AC biasing circuit. A comparison is made of the requirements and design features of the different tuner designs with special emphasis on the designs in the process of being developed and tested.<<ETX>>
Magnetic Fields in Small Ferrite Bodies with Applications to Microwave Cavities Containing Such Bodies
The microwave magnetic field in a small ferrite sphere and thin circular cylinder is found in first approximation. In a circularly polarized exciting field the internal field is again circularly polarized. The ratio of the internal field to the exciting field is 3(µ±α+2)-1 for the sphere and 2(µ±α+1)-1 for the cylinder. When the exciting field is linearly polarized the internal field is elliptically polarized. The expressions derived are applied to the calculation of the detuning and change of Q of microwave resonators containing ferrite spheres, cylinders and discs. Conversely they provide a means for the calculation of the elements of the permeability tensor from the experimentally observable change in cavity characteristics. The ferromagnetic resonant frequencies calculated from the present formulas are in agreement with those obtained by Kittel by the use of demagnetizing factors.