Electromagnetic field and cutoff frequencies of the azimuthally rippled wall waveguide

The cylindrical waveguide with azimuthally periodic corrugations described by a sinusoidal function is analyzed. Relevant to magnetron and gyrotron in teractions, TE-mode oscillations are treated by deriving a dispersion relat ion-linking the cutoff frequency and corrugation parameters-upon expansion of the field quantities in terms of space harmonics. From numerical example s, the present paper examines how the geometrical properties (area and peri meter) of the corrugated cross section relates with the cutoff frequencies of 2 pi and pi modes having one radial variation. The waveguiding system st udied here with continuously corrugated azimuthal profile looks attractive to relativistic, slow-wave electron devices for it is more resistant to RF breakdown in comparison with traditional magnetron cavities with vane-type side resonators.