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In this article, by substituting the dielectric tensor in Maxwell’s equations and using the boundary conditions in a longitudinally magnetized plasma-filled coaxial elliptical waveguide, the dispersion relation in the considered configuration is derived. We study the energy and dynamic of an injected external electron with initial energy using radiation of an electromagnetic source in the considered waveguide having the considered hybrid mode. The trajectory and kinetic energy of an injected electron in the considered waveguide along the propagating axis and hybrid field components are plotted. The obtained differential equations are numerically solved by the fourth-order Runge–Kutta method, and the results are graphically presented. The effects of different parameters on the trajectory and kinetic energy of injected electrons are investigated. [ABSTRACT FROM AUTHOR]

In this paper, the finite-element method (FEM) is applied for an exact solution of the dispersion of hybrid electromagnetic waves excited in a novel combined elliptical waveguide. This special configuration is included of an elliptical metallic waveguide filled with a dielectric material, whereas two axial hollows with circular cross section have been created in it. A hollow is placed in one of focuses of the elliptical waveguide and second hollow is located in another focus or shifted from it. Two straight relativistic electron beams with the same currents and velocities in opposite directions are injected inside the hollows. Here, we apply an accurate approach in which the electromagnetic fields described by the FEM and satisfies boundary conditions at the interfaces of different regions. Then, the time growth rate of slow waves amplified by the electron beam is numerically calculated. The excited waves are in microwave range. The effects of accelerating voltage and current density of electron beams, and geometrical parameters such as radius and location of electron beam, on the frequency spectra, the growth rate, and profiles of axial electric and magnetic fields of excited slow waves are studied. Our research shows, the novel waveguide studied in this paper is superior to other waveguide structures in wave amplification with applying minimum input electrical power. [ABSTRACT FROM AUTHOR]

The dispersion relation of electromagnetic waves in a rippled-wall elliptical waveguide with a degenerate plasma column protected by an elliptical annular dielectric layer is theoretically investigated. Using the linear field theory, the dispersion relation of electromagnetic waves in a rippled-wall elliptical waveguide with a plasma rod and an elliptical annular dielectric is obtained. In addition, by injecting a finite thick annular intense relativistic electron beam in this waveguide, the dispersion relation of these waves is investigated. In addition, a cold and uniform plasma-filled traveling wave tube with sinusoidally corrugated slow-wave structure is driven by a finite thick elliptical annular intense relativistic electron beam with the entire system immersed in a strong longitudinal magnetic field. Using the linear field theory, the dispersion relation for the elliptical relativistic traveling wave tube is derived. [ABSTRACT FROM PUBLISHER]

The dynamics of an electron in the fields associated with a transverse magnetic wave propagating inside circular and elliptical waveguides is analytically studied. The field components of the TMmr mode in the circular and elliptical waveguides are calculated. The relativistic momentum and energy equations are solved for the electron when it is injected along the direction of mode propagation. The deflection angle and the acceleration gradient of the electron during its shift along the waveguide are obtained. Furthermore, it is found that the acceleration gradient and deflection angle depend strongly on the parameters of the microwave and the dimensions of the waveguide. Finally, the cutoff frequency for the two cases of evacuated waveguide and plasma-filled waveguide is calculated. [ABSTRACT FROM PUBLISHER]