Dr. Art Vetter

Accelerator Physics

Boeing Phantom Works

Introduction to multicell cavity

General first order perturbation theory

Perturbation matrix in terms of cell frequency errors

Field profile perturbations in terms of cell frequency errors

Finding and correcting the frequency errors that account for observed profile

Strategy for employing active tuners

Standing wave accelerator structures typically require adjustment of the resonant frequency of each cell in order to produce a reasonably

uniform excitation profile in the desired accelerating mode. First order perturbation theory can provide an estimate of the field profile distortions produced by deviations from the ideal resonant frequency of the cells. These results can be inverted to allow the frequency errors to be inferred from the measured excitation profile of a structure. A few iterations allow the field profile to be made flat to within a percent or two. Finally, the deployment strategy for active tuners is guided by the results of the perturbation analysis.