Schematic of the interaction space of the surface-wave oscillators with (a), (b) 1D and (c) 2D periodical gratings driven by a rectilinear sheet electron beams.
Dispersion curves of the normal surface waves for different values of corrugation depth : solid lines, quasi-optical approach; dotted lines, CST Microwave Studio simulations.
Quasi-optical simulation of excitation of eigenmodes above corrugated structure of finite length by initial electromagnetic pulse. (a) evolution of field amplitude, (b) field spectrum at the final stage corresponding to excitation of fundamental surface mode, (c) spatial distribution of partial wave-beam amplitude having one variation along the longitudinal z coordinate and exponential decay along the y coordinate ( , , ).
Nonlinear dynamics of surface-wave oscillator in the framework of a 2D quasi-optical model. (a) The time dependence of efficiency and oscillation frequency . Spatial distributions of partial wave-beams amplitudes (b) and (c) in the steady-state regime ( ≈ 0.3 kA/cm, , , , , , ).
Results of 2D PIC simulations of W-band surface-wave oscillator with a single-periodic structure for the same parameters as in Fig. 4 : (a) Temporal dependence of field amplitude, (b) oscillations spectrum corresponding to excitation of fundamental surface mode; (c) instant spatial structure of component of magnetic field at the (z, y) plane describing the interference between the partial waves .
(a) Dispersion characteristic of evanescent wave and intersection points with beam lines for different values of electron energy . (b) Dependence of electron efficiency and the power radiated in directions on electron energy , (c) the same for the temporal increment and detuning of steady-state oscillations frequency from the reference one (detuning of intersection point defined from (a) is plotted in dashed line).
Spatial distribution of partial wave-beams amplitudes in the BWO operation regimes, : (a), (b) an oversized waveguide b = 18 mm; (c), (d) a waveguide with small cross-section b = 3 mm.
Temporal gain vs. beam width for the first symmetrical (solid line) and anti-symmetrical (dashed line) modes.
Simulations of surface-wave oscillator based on 3D quasi-optical model for electron beam width : (a) Temporal dependence of amplitude , (b) spatial distribution of this amplitude in the steady-state regime in the cross-section y = const, (c) distributions of amplitude and phase at output cross-section ( = 0.3 kA/cm, , ).
The same as in Fig. 9 for the electron beam width . Solid line corresponds to excitation of symmetrical mode; dashed line corresponds to anti-symmetrical one.
Results of PIC simulations of W-band surface-wave oscillator with a single-periodic structure of a finite width : (a) Temporal dependence of field amplitude, (b) oscillations spectrum corresponding to the simultaneous excitations of several modes with different numbers of field variations over the transverse x coordinate; (c) instant spatial structure of component of magnetic filed at the (z, x) plane ( ).
(a) Diagram illustrating the coupling of the partial wave-beams on the 2D grating. (b) Dispersion diagram of a normal surface wave for infinite in the z and x directions 2D periodical grating.
Quasi-optical simulations of excitation of eigenmodes under 2D periodical grating of finite length = 19.6 cm and width = 27 cm by initial electromagnetic pulse. (a) Evolution of field amplitude, (b) field spectrum at the final stage corresponding to excitation of single surface mode. (c)–(f) Partial wave profiles for a fundamental mode in the different cross-sections. ( mm, mm).
CST simulation of selective excitation of a fundamental mode by initial electromagnetic pulse: (a) temporal dependence of field amplitude ,(b), (c) field spectrum at and correspondingly.
Instant spatial distribution of Hx and Hz components of magnetic field in the different cross-sections.
Temporal dependencies of (a) the efficiency and (b) the radiation power emitted in the different directions during the onset of a steady-state regime in a 2D surface-wave oscillator. (c) Spatial distributions of partial wave-beam in the steady-state regime ( ≈ 0.3 kA/cm, , = 19.6 cm, = 27 cm, mm, mm, , ).
PIC simulations of a W-band 2D surface-wave oscillator: (a) temporal dependence of the .
(a)–(c) Instant spatial distribution of and components of magnetic field in the different cross-sections.
Article metrics loading...
Full text loading...