Field Profile Flattening for Multi-Cell Accelerator Structures

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.