Magnetized Plasma Waveguide Research Articles

Two-stream instability of relativistic electron beam in magnetized plasma waveguide: nonlinear logarithmic electrodynamics model

Two-stream instability of relativistic electron beam in magnetized plasma waveguide: nonlinear logarithmic electrodynamics model

Electron acceleration in a warm, motional, magnetized plasma‐filled waveguide by twisted electromagnetic wave pulses

AbstractThis paper studies the acceleration of an electron in a magnetized plasma waveguide caused by the interaction between the twisted electromagnetic wave and the plasma wave in a motional plasma. The spatial dependence of the amplitude and phase of the twisted TM mode has been derived by solving the wave equation. With appropriately assigned initial values, total electron energy gain can be calculated using numerical calculations. Numerical results show that plasma motion, as long as the twisted electromagnetic wave pulse, significantly affects electron acceleration during an electron's passage through the waveguide.

Dissipative instabilities in beam-plasma systems

It is known that all types of beam-plasma instabilities (Cherenkov, cyclotron, etc.) at a high level of dissipation turn into dissipative instability (DI). Until recently, only one type of DI was known in the beam-plasma interaction theory. Its maximal growth rate depends on the beam density n b and the collision frequency ν in the plasma as . However, recent studies have shown the existence of two new, previously unknown types of DI. Here, the new DI are briefly justified from the same viewpoint. This became possible due to the developed approach, which makes it possible to solve completely the classical problem of the development of an initial perturbation for various flow instabilities. The first new DI arises in the results of solving of the problem in systems with weak beam-plasma coupling. Its maximal growth rate is inversely proportional to frequency of collisions in plasma . The second new DI manifests itself in the results of the same problem in a magnetized plasma waveguide with an over-limiting e-beam. Its maximal growth rate is . Besides, the presented method of solving the classical problem deserves attention in itself as it is applicable to all instabilities caused by relative motion of plasma components (all types of beam-plasma instabilities, Buneman instability, etc.).

Electromagnetic Fields and Trajectory of Injected Electron Inside an Elliptical Coaxial Magnetized Plasma Waveguide

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.

A theoretical investigation of the presence of the azimuthal backward waves (ABWs) and their amplification in a magnetized plasma waveguide with two annular rotating energy sources

In this paper, the azimuthal backward waves (ABWs) in a magnetized plasma waveguide are studied. The waveguide is made of the loss-free metallic cylindrical wall and a dielectric annular layer and a magnetized plasma column in it. There are two annular rotating electron beams as the energy sources in the waveguide. The inner annular rotating electron beam (IAREB) is in the plasma region and the outer annular rotating electron beam (OAREB) is on the dielectric layer. The generation of ABWs as a possible consequence of the presence of two annular electron beams is proved by using Poynting’s theorem in the mentioned configuration. Also, it is observed that the width of allowed and forbidden frequencies of ABWs in the considered waveguide can be enhanced and shifted to the higher frequency side by changing the fundamental physical parameters. In addition, the effective factors on the frequency spectrum and growth rate of ABWs such as the geometric dimensions, the dielectric constant of the dielectric layer and electron plasma frequency of the annular electron beams are studied.

Cutoff frequencies of accelerating modes propagation inside a cylindrical waveguide filled with radially inhomogeneous magnetized plasma

The cutoff frequencies of accelerating hybrid EH0l mode (l = 1, 2, 3, and 4) propagation are studied in a cylindrical waveguide filled with radially inhomogeneous plasma in the presence of an external static magnetic field applied along the waveguide axis. To drive the analytical cutoff equations, a model based on the Bessel-Fourier expansion, which considers strong spatial dispersion and a finite external magnetic field, is utilized. In order to examine the integrity of the cutoff equations, the well-known cutoff expression related to the hybrid EH wave in a homogeneous magnetized plasma waveguide is recalculated with the help of a new model. The cutoff equations are solved numerically, and the effects of the external magnetic field and plasma density are investigated on the cutoff frequencies of the EH0l modes (l = 1, 2, 3, and 4) in the particular waveguide with a radius of 2.1 cm. By studying the effect of the waveguide radius on the cutoff frequencies, it is revealed that the waveguide radius plays a decisive role in the behavior of the cutoff frequencies with the external static magnetic field and plasma density. It is found that a critical radius can be realized for the waveguide so that the cutoff frequency treatment with the external magnetic field and plasma density is reversed in it.

Dispersion characteristics and excitation of space-charge and cyclotron modes in inhomogeneous warm plasma waveguide

In this paper, we are going to investigate the effects of plasma parameters on dispersion characteristics of electrostatic modes in a cylindrical inhomogeneous warm magnetized plasma waveguide. To this aim, the radial inhomogeneity for different characteristic length with strongly spatial dispersion are taken into account. Due to radial inhomogeneity of plasma, all essential equations for studying the properties of dispersion are calculated in Bessel–Fourier and differential Bessel–Fourier expansion. Moreover, two cases of strong and weak magnetic fields are considered for the analyses. We show that there was just an interval in which the space-charge and cyclotron modes are excited. We called it the Longitudinal Wavenumber Excitation Interval that is due to the thermal effect consideration. The effect of different radial inhomogeneity characteristic length on the dispersion properties is also studied in this work.

Analysis of Landau damping in radially inhomogeneous plasma column

The Landau damping behavior in a cylindrical inhomogeneous warm magnetized plasma waveguide has been studied. The radial inhomogeneity for different characteristic lengths (L0) with strong spatial dispersion has been taken into account. The analyses have been considered for two limits and . Due to the radial inhomogeneity of the plasma, all essential equations for studying the Landau damping are calculated in the Bessel–Furrier and differential Bessel–Furrier expansions. The dependence of Landau damping on the inhomogeneity, temperature and external magnetic field for electrostatic modes is scrutinized and described in detail through numerical calculations. The associated numerical results are presented and discussed.

Finite magneto-static field effect on the excitation of THz hybrid modes in an elliptical metallic plasma waveguide with two energy sources

The effect of finite magnetic field on the excitation, generation, and amplification of slow electromagnetic waves at THz frequency in a magnetized plasma waveguide with elliptical cross section is investigated. In configuration mentioned above, there are two electron beams with opposite directions as energy sources, and the role of magnetic field power on the appearance of the number of dispersion branches is analysed. It is shown that with increasing magnetic field, the field profiles of hybrid waves are increased in regions where the interaction of waves and electron beams are optimized. It is also shown that by applying the magnetic field, generation of THz frequencies can be easy to obtain in comparison to the unmagnetized case. In other words, by applying a finite magnetic field, better THz excitation occurs in the absence of high accelerating voltage. Increasing growth rate which can be achieved with increasing static magnetic field is also investigated. In this paper, because of high longitudinal velocity of electron beams, the effect of finite magnetic field on the fluctuations of electron beams is considered negligible.

Filamentation instability of electron/ion beams in magnetized plasma waveguide

AbstractThe filamentation instability due to the interaction of two relativistic electron and ion beams with magnetized plasma in a waveguide is studied within the framework of a macroscopic cold fluid description. It is assumed that the background plasma provides charge and current neutralization of the injected beams. The dispersion relation is obtained by solving wave eigenvalue equation. The resulting dispersion equation is analyzed numerically over a wide range of system parameters. It is found that the velocity difference factor can strongly affect the filamentation instability.

Optical and magneto-optical properties of one-dimensional magnetized coupled resonator plasma photonic crystals

In this paper, the optical and magneto-optical properties of one-dimensional magnetized coupled resonator plasma photonic crystals have been investigated. We use transfer matrix method to solve our magnetized coupled resonator plasma photonic crystals consist of dielectric and magnetized plasma layers. The results of the change in the optical and magneto-optical properties of structure as a result of the alteration in the structural properties such as thickness, plasma frequency and collision frequency, plasma filling factor, number of resonators and dielectric constant of dielectric layers and external magnetic field have been reported. The main feature of this structure is a good magneto-optical rotation that takes place at the defect modes and the edge of photonic band gap of our proposed optical magnetized plasma waveguide. Our outcomes demonstrate the potential applications of the device for tunable and adjustable filters or reflectors and active magneto-optic in microwave devices under structural parameter and external magnetic field.

Linear theory of the electron beam-wave-plasma interactions in a magnetized plasma waveguide

The theoretical study on the electron beam-wave interactions in a plasma waveguide immersed in a finite magnetic field is given in the article, in which both the plasma and the electron beam are considered as special media. Making use of the constitutive transformation and the Lorentz transformation in the four-dimensional space, the permittivity tensor of the stationary magnetized plasma, the permittivity tensor, the permeability tensor, and the chiral tensor of the electron beam in the rest (laboratory) frame are acquired. Therefore, two coupled wave equations for the magnetized plasma and electron beam have been obtained and the dispersion relations are then achieved by solving these coupled equations together with the boundary conditions including the surface current density due to the ripple of the plasma/beam. As an example of the applications of this approach, the beam-wave interactions in a practical plasma Cherenkov maser have been studied and the numerical calculations have been carried out in detail. It has been found that the present approach is more accurate and can provide clearer mode information for the electron beam-wave interactions in a magnetized plasma waveguide. This approach can be exploited in a number of electron beam-wave interaction systems including some kinds of free electron devices, plasma filled Cherenkov radiated free electron lasers and masers.

Azimuthal electromagnetic surface waves in a rod dielectric magnetized plasma waveguide and their excitation by an annular relativistic rotating electron beam

The dispersion relation of azimuthal electromagnetic surface waves in a rod dielectric magnetized plasma waveguide is obtained. It is investigated that these waves in E-type can be excited by a thin annular relativistic rotating electron beam (TARREB). The effects of the rotating velocity of beam, radius TARREB, on the frequency spectra and growth-rate coefficient are presented.

Dispersion properties and field structures of eigenmodes of nonuniform plasma waveguides in a longitudinal magnetic field

We study the field structure and dispersion properties of a hybrid eigenmode guided by a nonuniform magnetized plasma waveguide. It is shown that the rotational and quasi-potential waves contribute to the formation of such a mode in the whistler frequency range. Depending on the plasma density, the rotational component of the hybrid mode is determined by either waves with complex transverse wave numbers or whistler waves, or by true surface waves. In the presence of an axial nonuniformity of the plasma in a channel, the transverse field structure of the propagating mode changes, which is stipulated by changes in both the values of transverse wave numbers and their dependence on the radial coordinate. It is found that the spectrum of axial wave numbers of eigenmodes of a plasma waveguide undergoes a pronounced condensation when smoothing the waveguide walls. The damping of the hybrid mode of a nonuniform waveguide due to electron collisions is found and it is shown that collisional losses determine the damping of waves trapped in the waveguide in the experiments on ionization self-channeling of whistler waves. We have found the effect of “displacing” the strong field from the inner core to the background outer region of the waveguide with increasing plasma density on its axis and broadening background region.

Evaluation of mode fields in a magnetized plasma waveguide and electron acceleration

The fields for the fundamental H10 mode are evaluated in a rectangular waveguide filled with plasma under the effect of external static magnetic field applied along the direction of propagation of the mode (z-axis). In the presence of magnetic field the components Hy and Ex are not suppressed and the mode gets modified. Two-dimensional variations of the mode fields are presented and the effects of magnetic field and plasma density on the cutoff frequency, guide wavelength and the dispersion relation of the mode are studied. It is seen that the guide wavelength gets larger for the higher plasma density and stronger magnetic field; however, it decreases when the waveguide width and the microwave frequency are increased for other fixed parameters. The trajectory of the electron is analyzed under the effects of various parameters, when the electron is injected in the waveguide along the direction of mode propagation. Two cases are discussed when ωp<Ωc and ωp>Ωc. Under such situation, the electron acceleration is also studied and it is observed that the acceleration gradient is increased with the microwave frequency. However, it gets reduced and lower energy gain is obtained under the effect of increasing plasma density and magnetic field.

Effect of the ponderomotive force on the development of beam-plasma instability

The amplitude of the wave generated in a plasma during the development of beam-plasma instability is nonuniform in the longitudinal direction. The ponderomotive force associated with this nonuniformity leads to a redistribution of the plasma density; as a result, the wave amplitude and its spatial distribution change. As the beam current grows, the ponderomotive force plays an increasingly important role and radically changes the mechanism by which the beam-plasma instability saturates. Ion acoustic waves generated by the ponderomotive force propagate in the direction opposite to the propagation direction of the beam, thereby ensuring distributed feedback and giving rise to a strong low-frequency self-modulation of the wave amplitude and phase. Results are presented from experimental investigations of the self-modulation regime of the beam-plasma instability in a magnetized plasma waveguide. Theoretical estimates of the parameters of the low-frequency self-modulation agree well with the experimental data.

Electron beam excitation of a potential well in a magnetized plasma waveguide

The evolution and properties of a potential well being excited in a magnetized plasma-filled waveguide by a hot electron beam have been investigated. An equation of KdV-type describing the potential well has been obtained. It is shown that a potential shock is formed near the potential well, the front of the well is steeper than the back, the width of the well decreases with increasing amplitude. The well is determined by two modes with a linear dispersion relation: by the mode in a magnetized plasma-loaded waveguide and by the electron-acoustic mode.

Experimental verification of cyclotron absorption of polarized electromagnetic waves in a plasma waveguide

This paper presents the results of an experiment dealing with the absorption of electromagnetic waves in a longitudinally magnetized plasma waveguide at electron cyclotron frequency. Our results demonstrate, under different operating conditions, the importance of the polarization of the incident waves as well as the linear behavior of the plasma density as a function of the absorbed power. The gas used in this study was argon.

Nonlinear electromagnetic wave transformation in a longitudinally magnetized plasma waveguide

Deals with an experimental study of electromagnetic wave transformation in a longitudinally magnetized plasma waveguide (LMG plasma column). The authors have obtained the line averaged plasma density dependence with the incident power launched into the plasma. The experiments were carried out in argon. The paper presents evidence of anomalous absorption of an intense right hand circularly polarized wave (RHCP wave) at high magnetic fields.

Three-wave processes in a magnetized plasma waveguide containing a thin beam

Three-wave processes in a magnetized plasma waveguide containing a thin beam