Numerical analysis of slow-wave instabilities in oversized sinusoidally corrugated waveguide driven by finitely thick annular electron beam

There are three kinds of model for beam instability analyses, which are based on solid beam, infinitesimally thin annular beam, and finitely thick annular beam. In high power experiments, the shape of electron beam is annulus having finite thickness. We present slow-wave instability driven by finitely thick annular beam in oversized sinusoidally corrugated waveguide for K-band operation. Our analysis is based on a new version of self-consistent liner theory considering three dimensional beam perturbations. The dependence of Cherenkov and slow cyclotron instabilities on the annular thickness and guiding magnetic field are examined. (author)