Schemes of a co-axial (a) and cylindrical (b) surface-wave oscillators with 2D periodical gratings: (1)—hollow electron beam, (2)—outer corrugated conductor, and (3)—inner regular conductor, (c) unfolded corrugated surface (the directions of propagation of the partial wave beams are shown).
Dispersion curves of the normal surface waves with different azimuthal indices m plotted at different scales ( ). Dashed lines are the light cone.
Results of CST simulation of eigenmodes excitation by an initial e.m. pulse. Field spectrum is shown at the final stage of evolution when modes with various numbers of azimuthal variations are separated out (r0 = 2 cm, = 10 cm, mm, and mm).
Dependence of the increments of different azimuthal modes on the normalized system perimeter .
(a) The time dependence of normalized efficiency and frequency shift . (b) Temporal dependencies of different azimuthal mode amplitudes during the onset of a steady-state regime on a symmetrical mode m = 0 for .
(a) The time dependence of normalized efficiency and frequency shift . (b) Temporal dependencies of different azimuthal mode amplitudes during the onset of a steady-state regime on a symmetrical mode m = 0 for with all other parameters as in Fig. 5 .
Spatial distributions of partial wave-beams (a) and (b) in the steady-state regime (all parameters as in Fig. 5 ).
PIC simulations of a Ka band cylindrical surface-wave oscillator: (a) radiation spectrum, (b) the decomposition of the output radiation in the mode of regular cylindrical waveguide, (c) and (d) the spatial distribution of the longitudinal component of the electrical and magnetic fields in the steady-state oscillations regime.
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