Accelerator RF Systems
Daniel Boussard, Retired
This course is intended to give an overview of rf systems for circular accelerators. In the first part, the concepts and techniques related to accelerating cavities will be presented: modes of oscillation of a cavity, equivalent circuits and parameters, and multicell cavities (in traveling or standing wave modes). Radiofrequency losses in cavities are of prime importance for the rf system designer and often lead to the choice of the most appropriate technology for a given application. Coupling the cavity to the outside world, namely the rf power generator and the beam current, will be the subject of the second part of the course. It will cover the damping of higher modes and the analysis of steady beam loading. The commonly used power generators, tetrodes and klystrons will be described. Transient periodic beam loading becomes important in modern, high-current machines with beam gaps; its consequences on machine performance and on rf system design will be presented. In the last part of the course, the dynamics of the rf system with beam will be analyzed, in particular its stability limits and the effect of various feedback loops. Prerequisites: Accelerator Physics.