Design Process for Synchrotron RF Cavities Loaded With Magnetic Ring Cores

Cavities loaded with magnetic ring cores are often used in synchrotrons if the desired operating frequency is in the lower megahertz range. The properties of such a cavity are strongly determined by the ring cores. However, other cavity components also have an important influence. During the design phase of such a cavity, full-wave simulations are not the first choice because computational modeling of parts like magnetic ring cores is complicated and because the influence of the ring core material data is often larger than that of the cavity geometry. In the past, these types of cavities have often been built without performing 3-D simulations. While standard acceleration cavities can be developed rather accurately by experienced designers, the coupling between amplifier and cavity or the development of more advanced cavity systems e.g., for barrier bucket operation or longitudinal feedback still bears some risks. In this article, at hand, we describe a new development process that was successfully used for the development of an MA-loaded broadband cavity. It is based on the broadband lumped-element circuits for single-ring cores. We used standardized ring-core measurements to obtain the required impedance data, but analytical methods can, in general, be used as well. The lumped-element circuits for the ring cores are used in a PSpice model of the whole cavity, allowing for simulations in frequency and time domain. We will show that the simulation results are in good agreement with measurements of the overall cavity.