Thin Annular Relativistic Electron Beam Research Articles

The Effects of a Transverse Anisotropy Dielectric Rod in Excitation and Amplification Phenomena of Hybrid Electromagnetic Waves in a Cylindrical Metallic Waveguide

In this paper, a novel waveguide made of a hollow long metallic cylindrical column with a transverse anisotropy dielectric rod (TADR) is studied. The dispersion relation of hybrid electromagnetic waves is obtained in this structure, and its diagram variations will be investigated. The effects of dielectric permittivity coefficients of TADR on the dispersion relation of slow waves is studied. The mechanism of wave generation and its amplification phenomena by a thin annular relativistic electron beam are investigated for hybrid modes. Also, the graphs of operating frequency and the graphs of growth rate will be presented for the waves during the electron beam injection. The computations have done for terahertz hybrid waves.

About background plasma effects on excitation and generation of the waves in a cylindrical metallic waveguide with anisotropic dielectric rod

In this work, the dispersion relation of hybrid electromagnetic waves propagating in a novel plasma cylindrical waveguide with a cold collisionless unmagnetized plasma column and a transverse anisotropy dielectric rod (TADR) is investigated. The dispersion diagram of the hybrid waves in this configuration is obtained. The effects of dielectric permittivity coefficients of TADR on the dispersion relation of slow waves are studied. Excitation of the waves by a thin annular relativistic electron beam (TAREB) will be presented. Furthermore, the diagrams of the operating frequency and time growth rate are obtained. In continuation, the accelerating voltage, the current density of TAREB, and the radius of the plasma column on the growth rate will be discussed.

Excitation of THz hybrid modes in an elliptical dielectric rod waveguide with a cold collisionless unmagnetized plasma column by an annular electron beam

The dispersion relation of electromagnetic waves propagating in an elliptical plasma waveguide with a cold collisionless unmagnetized plasma column and a dielectric rod is studied analytically. The frequency spectrum of the hybrid waves and the growth rate for excitation of the waves by a thin annular relativistic elliptical electron beam (TAREEB) is obtained. The effects of relative permittivity constant of dielectric rod, geometrical dimensions, plasma frequency, accelerating voltage, and current density of TAREEB on the growth rate and frequency spectra of the waveguide will be investigated.

Terahertz electromagnetic wave generation and amplification by an electron beam in the elliptical plasma waveguides with dielectric rod

The propagation of electromagnetic waves in an elliptical plasma waveguide including strongly magnetized plasma column and a dielectric rod is investigated. The dispersion relation of guided hybrid electromagnetic waves is obtained. Excitation of the waves by a thin annular relativistic elliptical electron beam will be studied. The time growth rate of electromagnetic waves is obtained. The effects of relative permittivity constant of dielectric rod, radius of dielectric rod, accelerating voltage, and current density of the annular elliptical beam on the growth rate and the frequency spectra are numerically presented.

The Rod Degenerate Plasma-Rippled-Wall Waveguide and Its Excitation by Relativistic Electron Beam Injection

The dispersion relation of electromagnetic waves in a rippled-wall waveguide with a degenerate plasma column protected by an annular dielectric layer is theoretically investigated. By injecting a thin annular relativistic electron beam (TAREB) in the region between dielectric and metallic cylinders in the aforementioned configuration as an energy source, the excitation of terahertz (THz) electromagnetic waves is investigated. Also, the dependence of dispersion relation and time growth rate on the radius of the dielectric, the corrugation amplitude, and period is studied. Furthermore, it is found that the presence of the degenerate plasma rod in the rippled-wall waveguide leads to obtain high-frequency modes in the THz frequency region. Finally, the electric-field profiles in this waveguide are plotted.

Excitation of THz symmetric TM-modes in a cylindrical metallic waveguide with an axial magnetized degenerate plasma rod by an electron beam

The dispersion relation of symmetric electromagnetic TM-modes in a cylindrical metallic waveguide with a magnetized degenerate plasma column protected by an annular dielectric layer are obtained. The permissible frequency regions for slow E-modes (TM) are presented. In addition, the time growth rate for excitation of these waves by a thin annular relativistic electron beam (TAREB) is studied. The dependency of time growth rate on the strength of the external magnetic field, hole plasma frequency and accelerating voltage are investigated.

THE THEORETICAL INVESTIGATION OF THz ELECTROMAGNETIC WAVES IN A ROD DEGENERATE PLASMA-WAVEGUIDE

By using the Fourier components of dielectric tensor elements of cold collisionless degenerate plasmas, the dispersion relation of electromagnetic waves in a cylindrical metallic waveguide with a degenerate plasma column protected by an annular dielectric layer are obtained. The permissible frequency regions for slow and fast waves in E-mode (TM) are presented. Furthermore, the graph of cutoff frequency versus the radius of plasma column for the fast waves is investigated. In addition, the time growth rate for excitation of symmetric slow E-modes (TM) by a thin annular relativistic electron beam (TAREB) is studied. The graph of time growth rate respect to radius of dielectric layer and accelerating voltage are presented.

Time growth rate of symmetric TM mode of a rod dielectric Cerenkov plasma maser

The dispersion relation of symmetrical TM waves (usual operating mode of a traveling wave tube) propagating in a Cerenkov maser including a thin annular relativistic electron beam (TAREB), a strongly magnetized plasma column, and a dielectric rod is investigated. The effects of relative permittivity constant of dielectric rod, accelerating voltage, radii of the rod, TAREB, and plasma column as well, on the frequency spectra and growth-rate coefficient are presented. The conditions under which the growth rates are maximum are studied as well.

Spatial growth rate and field profiles of symmetric mode in a rod dielectric Čerenkov maser with a magnetized plasma column

By numerically solving the exact dispersion equation, the dispersion relation of symmetrical TM waves propagating in a Čerenkov maser including a thin annular relativistic electron beam (TAREB), a strongly magnetized plasma column, and a dielectric rod is investigated. The effects of accelerating voltage, radii of TAREB and plasma column as well, on the frequency spectra and spatial growth-rate coefficient are presented. The axial electric field profiles during the wave amplification and the conditions under which the spatial growth rates are maximum are presented.

Excitation of Microwave by a Thin Annular Relativistic Electron Beam in a Plasma-Filled Dielectric-Loaded Coaxial Cylindrical Waveguide

A new type of slow-wave structure, i.e., plasma-filled dielectric-loaded coaxial cylindrical waveguide with a dielectric ring tightly enclosing the inner conductor, is developed. The collision between electrons and ions in the background plasma is taken into account. The microwave generation based on the Cherenkov effect excited by a thin annular relativistic electron beam in the new slow-wave structure is examined by use of the self-consistent linear field theory, considering the effect from this kind of collision via the collision frequency n/sub e,i/ term. The dispersion equation of the beam-wave interaction with a complex value of angular frequency is derived. The effects of the plasma angular frequency and collision frequency on the dispersion characteristics, i.e., the output frequency and the wave growth rate of the microwave radiation, are calculated and discussed. It is clearly shown that the microwave radiation excited by the beam-wave interaction results from the coupling between the slow TM modes propagated along the slow-wave structure and the negative-energy space-charge wave propagated along the relativistic electron beam.

Dielectric Cherenkov maser with a magnetically confined plasma column in a dielectric lined slow-wave waveguide

The effect of the strong external magnetic field is studied on the dielectric Cherenkov maser, which is included with an axial thin annular relativistic electron beam and a plasma column in a dielectric lined slow-wave waveguide. The dispersion equations of the beam-wave interaction are derived. The growth rates of the wave are obtained, and the effects of the accelerating voltage, beam current and the background plasma density on the growth rate of the wave are numerically calculated, discussed, and compared in the presence and absence of external magnetic field.

Cerenkov radiation excited by a thin annular relativistic electron beam in a slow-wave structure consisting of an annular-plasma-filled cylindrical waveguide with a dielectric lining

By using a self-consistent and relativistic field theory, Cerenkov radiation for a configuration in which a thin annular relativistic electron beam (TAREB) propagates through an annular-plasma-filled dielectric lining enclosed within a perfect conducting wall is studied in the absence of a longitudinal guided magnetic field. Determinant dispersion equations of the beam–wave interactions for (a) the TAREB inside the annular plasma; (b) the TAREB penetrating through the annular plasma; and (c) the TAREB outside the annular plasma and the simultaneous condition producing the Cerenkov radiation are derived. These dispersion equations show that the beam–wave interaction results from the coupling of the TM mode in the annular-plasma-filled dielectric lined slow-wave waveguide to the beam mode via the electron beam. Finally, the dispersion equations are directly solved numerically, and the operation frequency and the growth rate of the system are obtained.

Excitation of Slow Electromagnetic Waves in a Dielectric-Lined Waveguide Having a Thin Annular Plasma Sheet

Excitation of slow electromagnetic waves for a configuration, in which a thin annular relativistic electron beam (TAREB) propagates through a cylindrical, dielectric-lined waveguide having a thin, annular plasma sheet at the same radial position as the TAREB, is studied in the presence of an infinite longitudinal guide magnetic field. Determinant dispersion equation is derived and directly numerically solved. The operation frequency and the growth rate of the waves are obtained and discussed.

Modulating electron beams for an X band relativistic klystron amplifier

A large diameter thin annular intense relativistic electron beam was modulated at a frequency of 10 GHz. The electron beam propagated inside a narrow annular drift tube in which gaps feeding radial cavities were inserted. An external source injected microwave power of 180 kW into a single input cavity followed by a simple idler structure. A stable 10 kA rf current modulation was induced on the 400 keV electron beam.

Dielectric Čerenkov maser with a plasma column in a dielectric lined slow-wave waveguide

Dielectric Čerenkov maser with a plasma column in a dielectric lined slow-wave waveguide is studied in the absence of a longitudinal guided magnetic field by use of a fully self-consistent and relativistic field theory. Determinantal dispersion equations of the interaction of a thin annular relativistic electron beam (TAREB) with the wave are derived for the TAREB inside and surrounding the plasma column, respectively. These dispersion equations show that the beam–wave interaction results from the coupling of the transverse-magnetic (TM) mode in the dielectric lined slow-wave waveguide with the plasma column to the beam mode via the electron beam. Finally, the dispersion equations are directly solved numerically, and the cutoff frequency, the operation frequency, and the growth rate of the wave are obtained.

ANALYSES OF BEAM-WAVE INTERACTION IN A DIELECTRIC LINED SLOW-WAVE WAVEGUIDE WITH A PLASMA COLUMN

A new type of slow-wave system (SWS) for the beam-wave interaction——putting a plasma column into a dielectric-partially-filled waveguide, is presented. By use of the linear self-consistent field theory, the interaction of a relativistic electron beam with the wave in the SWS is analysed. Determinative dispersion equations are derived for a thin annular relativistic electron beam propagating through the SWS surrounding and existing inside the plasma column, respectively. These dispersion equations are directly solved numerically, and the cut-off frequency, the operation frequency and the growth rate of the waves are obtained. Finally, the effects of the parameters of the plasma column on them are discussed.

LINEAR THEORY OF UNMAGNETIZED PLASMA FILLED DIELECTRIC CHERENKOV MASER

By use of the self-consistent linear field theory, three-dimensional perturbation of electrons affected by the perturbed electromagnetic fields is discussed. And Cherenkov radiations excited by a thin annular relativistic electron beam in a unmagnetized-plasma-filled, dielectric lined slow-wave waveguide are analysed. The dispersion equation and the wave growth rate of the interaction of the electron beam to the waveguide modes with arbitrary azimuthal mode number are derived. It′s clearly shown that the Cherenkov radiation results from the coupling of the waveguide mode in the unmagnetized-plasma-filled, dielectric lined slow-wave waveguide to the beam mode via the electron beam. Finally, the effects of plasma density on the dispersion relation and the wave growth rate are calculated and discussed.

Microwave generation by excitation of a plasma-filled slow wave structure

An axial relativistic electron beam passing through a slow wave structure is unstable to an electromagnetic perturbation whose phase velocity equals the velocity of the beam. This phenomenon of Cherenkov emission is the basis of all traveling wave tubes. In this paper, through the use of self-consistent linear field theory, the electron three-dimensional perturbation affected by the perturbed electromagnetic fields is discussed. Cherenkov radiations excited by a thin annular relativistic electron beam and a solid relativistic electron beam in a plasma-filled slow-wave structure are analysed in detail. The dispersion equations of the beam-wave interaction are derived. It is clearly shown that the beam-wave interaction results from the coupling of the TM mode in the plasma-filled slow-wave structure to the beam mode via the electron beam. Finally, the growth rates of the wave are obtained, and the effects of the background plasma density and the electron beam radius on the growth rate of the wave are calcul...

Cherenkov radiation with arbitrary azimuthal mode number excited in a plasma-filled slow-wave waveguide

On the basis of the reference [1], excitation of Cherenkov radiation with arbitrary azimuthal mode number by a thin annular relativistic electron beam in a plasma-filled dielectric-lined slow-wave waveguide is studied in this paper. A determinantal dispersion equation is obtained. This general dispersion equation is valid for arbitrary azimuthal mode number, and the growth rate of the wave is derived from it. Finally, the effects of the background plasma density on the dispersion relation, the background plasma density and the electron beam radius on the growth rate of the wave are presented. Formulas and results offerd in this paper are general, and are of particular value of reference to the beam-wave interaction in azimuthally unsymmetrical slow-wave waveguide.

Excitation of microwave by an annular electron beam in a plasma-filled dielectric lined waveguide

An axial relativistic electron beam passing through a slow wave structure is unstable to an electromagnetic perturbation whose phase velocity equals the velocity of the beam. This phenomenon of Cherenkov emission is the basis of all traveling wave tubes. In this paper an excitation of Cherenkov radiation by a thin annular relativistic electron beam in a plasma-filled dielectric-lined waveguide is analysed by use of the self-consistent linear theory. The effect of the thin annular electron beam on the beam-wave interaction is completely described by a jump condition. The dispersion equation and the simultaneous condition of the beam-wave interaction are derived. Finally, the growth rate of the wave is obtained, and the effect of the background plasma density and the electron beam radius on the growth rate of the wave are presented.