Modeling the influence of lossy dielectric loads in gyroklystron cavities

Summary form only given. The gyroklystron amplifier code MAGYKL has recently been adapted to permit rings of absorbing dielectric material to be included in the specification of the cavities, and to determine their influence on the cavity field profiles and beam interaction. Such rings are employed experimentally to obtain the desired ohmic-Q of each cavity to achieve optimum amplification and efficiency over a specified frequency bandwidth. In previous work, additional approximations have been necessary to model these devices successfully. It is shown that such approximations are not necessarily valid for all device parameter regimes. The fields for the complex cavities are derived using a scattering matrix method, extending the capabilities of the CASCADE code to model cylindrical cavities with sections having a thick dielectric ring against the outer wall. Cavity field structures, eigenfrequency and Q are obtained for complex cavities that consist of adjoining sections having differing radii and thicknesses of dielectric.