FDTD Analysis of Electromagnetic Reflection by Conductive Plane Covered with Magnetized Inhomogeneous Plasmas

A novel finite-difference time-domain (FDTD) methodology which incorporates both anisotropy and frequency dispersion at the same time is developed for electromagnetic wave propagation in anisotropic magnetoactive plasmas in this paper. The numerical verification of the method are confirmed by computing the reflection and transmission of right-handed/left-handed circularly polarized (RCP/LCP) wave through a magnetized plasma layer, with the direction of propagation parallel to the direction of the biasing field. And, the right-handed / left-handed polarized wave reflection coefficients for electromagnetic signals normally incident upon a conductive plane covered with a layer of magnetized plasma are computed using the new FDTD method. The parabolic electron-number density profile varies only in the direction perpendicular to the plane. The function dependence of reflection coefficients on the number density, collision frequency and external magnetic field is studied.     

Theoretical study of two-element array of equilateral triangular patch microstrip antenna on ferrite substrate

The radiation characteristics of a two-element array of equilateral triangular patch microstrip antenna on a ferrite substrate are studied theoretically by considering the presence of bias magnetic field in the direction of propagation of electromagnetic waves. It is found that the natural modes of propagation in the direction of magnetic field are left- and right-circularly polarized waves and these modes have different propagation constants. In loss-less isotropic warm plasma, this array antenna geometry excites both electromagnetic (EM) and electroacoustic plasma (P) waves in addition to a nonradiating surface wave. In the absence of an external magnetic field, the EM- and P-waves can be decoupled into two independent modes, the electroacoustic mode is longitudinal while the electromagnetic mode is transverse. The far-zone EM-mode and P-mode radiation fields are derived using vector wave function techniques and pattern multiplication approaches. The results are obtained in both plasma medium and free space. Some important antenna parameters such as radiation conductance, directivity and quality factor are plotted for different values of plasma-to-source frequency.     

磁化分层等离子体中电磁波传播特性研究

采用混合矩阵法,分析了磁化分层等离子鞘套对斜入射电磁波传播特性的影响,分别计算了不同入射角以及外加磁场下电磁波透射系数和极化特性的变化。以GPS导航信号右旋圆极化波(RCP)为例,研究了磁场、电子密度对电磁波右旋圆极化特性的影响。结果表明,外加磁场能够使右旋圆极化波在等离子体中的阻带向高频方向移动,此外,外加磁场能在一定程度上改善斜入射是圆极化波的极化特性,有利于GPS信号接收。     

Numerical analysis of the reflection and absorption of electromagnetic wave in nonuniform magnetized plasma slab

In this paper, a model for calculating the reflection and absorption powers of electromagnetic wave (EM wave) in nonuniform magnetized plasma slab is given out based on layer propagation theory. The effects of various plasma parameters and different values of magnetic field intensity on the reflected and absorbed powers are discussed. The results illustrate that the thickness of plasma seldom affects the reflection of radar wave, but it can broaden or reduce the absorption width. Meanwhile, the background magnetic field intensity has an influence upon the results, and it could change the resonance spectrum of magnetized plasma. We also find out that, with appropriate plasma density, collision frequency and magnetic field intensity, more than 90% of radar wave power can be absorbed and the resonant absorption band is about 2 GHz.     

Investigation of the properties of extraordinary mode in three-dimensional magnetized plasma photonic crystals with diamond lattices as Voigt effects are considered

In this paper, the properties of extraordinary mode for two types of three-dimensional magnetized plasma photonic crystals (3D MPPCs) composed of homogeneous dielectric and magnetized plasma with diamond lattices are theoretically investigated for electromagnetic (EM) wave based on a modified plane wave expansion (PWE) method, as Voigt effects are considered. As EM wave propagates in such 3D MPPCs, the EM wave can be divided in two modes due to the influence of Lorentz force. One is named extraordinary mode and another is ordinary mode. The equations for calculating the dispersive relationships for extraordinary mode as propagating through two types of structures (dielectric spheres immersed in magnetized plasma background or vice versa), are theoretically deduced. The influences of dielectric constant of dielectric, plasma collision frequency, filling factor, the external magnetic field and plasma frequency on the properties of extraordinary mode for both types of MPPCs are investigated in detail, respectively, and some corresponding physical explanations are also given. From the numerical results, it has been shown that not only the locations but also bandwidths and relative bandwidths of the photonic band gaps obtained by extraordinary mode for both types of 3D MPPCs can be manipulated by plasma frequency, filling factor, the external magnetic field and the relative dielectric constant of dielectric, respectively. However, the plasma collision frequency has no effect on the frequency ranges and relative bandwidths of PBGs for two types of 3D MPPCs. The locations of flatbands regions cannot be tuned by any parameters except for plasma frequency and the external magnetic field.     

Electromagnetic modelling of 3D periodic structure containing magnetized or polarized ellipsoids

Coupling matrix and coupling coefficient concepts are applied to the interaction of an incident plane wave with a regular array of small magnetized or polarized ellipsoids, placed in a homogeneous surrounding medium. In general case, the angle of incidence and polarization of the plane wave upon an array of ellipsoids can be arbitrary. In this model, it is assumed that all the ellipsoids are the same, and the direction of their magnetization is also the same. The direction of magnetization is arbitrary with respect to the direction of the propagation of the incident wave and to the boundary plane between the first medium, where the incident wave comes from, and the array material under study. Any magnetized or polarized ellipsoid is represented as a system of three orthogonal elementary magnetic radiators (EMR) and/or three orthogonal elementary electric radiators (EER). Mutual interactions of individual radiators in the array through the incident plane wave and corresponding scattered electromagnetic fields are taken into account. The electrodynamic characteristics — reflection from the surface of the semi-infinite array (in particular, containing uniaxial hexagonal ferrite resonators), transmission through the array, and absorption are analyzed.     

An exact solution of the relativistic equation of motion of acharged particle driven by a circularly polarized electromagnetic waveand a constant magnetic field

An exact solution is found for the relativistic equation of motion of a charged particle driven by a circularly polarized electromagnetic wave and a constant magnetic field. The explicit expressions of particle position and velocity are obtained for certain initial conditions. The results are of interest to the interaction of the high-power laser with the magnetized plasma, electromagnetically pumped free-electron laser with a guide magnetic field, propagation of electromagnetic wave signals through a re-entry plasma sheath in the presence of a strong magnetic field, and magnetic confinement plasmas     

太赫兹波在磁化等离子体中传输特性

建立了电磁波穿过磁化等离子体鞘套的一维模型,并采用数值分析方法对太赫兹（THz）电磁波在磁化等离子体鞘套中传播时的反射率、透射率和衰减值进行了计算仿真,分析了磁化条件下磁场强度、太赫兹波频率、等离子体鞘套厚度、等离子体碰撞频率和等离子体密度对太赫兹波在磁化等离子体鞘套中传播特性的影响。仿真结果表明:排除衰减波峰对应的频率范围,外加磁场有效降低了太赫兹波传输的衰减,在固定磁场强度下,衰减波峰两侧的衰减值均达到了5 dB以下,有效地解决了通信黑障问题。     

Frequency upshifting by an ionization front in a magnetized plasma

The interaction of a light wave with a relativistic ionization front in the presence of an applied DC magnetic field which is perpendicular or parallel to the incident wave is considered. In both cases, four transmitted modes are generated in the magnetized plasma by an incident linearly polarized wave. The frequency upshifts of the various modes are calculated and compared to the unmagnetized case. The corresponding reflection and transmission coefficients are also obtained. Finally, the density ripple associated with the free streaming mode in a magnetized plasma for the perpendicular case is discussed     

电磁波在磁化等离子体中传播的时域有限差分模拟

基于Z变换形式的时域有限差分法计算公式,模拟了传播方向垂直于磁化磁场的电磁波在磁化等离子体层中的传播.通过离散傅立叶变换,给出了电磁波通过均匀和非均匀磁化等离子体后的反射系数和透射系数随频率的变化关系.还给出了电磁波经过均匀磁化等离子体层后的反射和透射系数和理论值的对比.     

Damping rates of waves in a switched magnetoplasma medium:longitudinal propagation

The interaction of a circularly polarized electromagnetic wave with a switched-on magnetoplasma medium is considered. A static magnetic field in the direction of propagation is assumed to be present, resulting in longitudinal propagation. The incident wave splits into three waves whose frequencies are different from that of the incident wave. It is shown that these waves ultimately damp out if the plasma is even slightly lossy. The damping of the waves is interpreted in terms of their attenuation with distance and decay with time as they propagate in the lossy plasma. The attenuation-length and decay-time constants of the waves are obtained, and their dependence on the incident-wave frequency and the gyrofrequency is examined. Optimum parameters for an experiment to detect these waves are suggested     

FDTD Simulation of Electromagnetic Propagation in Magnetized Plasma Using Z Transforms

The electromagnetic propagation through a magnetized plasma slab is studied using the finite-difference time-domain method by means of the z transform The reflection and transmission coefficients of the magnetoactive plasma for the right-hand circularly polarized wave are presented. The comparison of the results of the Z transform and recursive convolution algorithms with analytic values indicates that the Z transform algorithm is more accurate than the recursive convolution algorithm. The Z transform algorithm overcomes the drawback that the recursive algorithm cannot predict the transmission coefficient of the magnetized plasma slab for the right-hand circularly polarized wave in the stop band.     

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在理想条件下,为了研究等离子体参数、填充率、入射角度和介质层相对介电常数对一维三元磁化等离子体光子晶体的禁带特性的影响,用由传输矩阵法计算得到的TE波任意角度入射时的左旋极化波(LCP)和右旋极化波(RCP)的透射系数来研究其禁带特性。结果表明,仅增加等离子体碰撞频率不能实现禁带宽度的拓展,改变等离子体频率、填充率和介质层的相对介电常数能实现对禁带宽度和数目的调谐。改变等离子体回旋频率能实现对右旋极化波的禁带的调谐,但对左旋极化波的禁带几乎无影响。入射角度的增大使得禁带低频区域带宽变大,而高频区域带宽则是将先减小再增大。     

Effect of Finite Rise Time on the Strength of the Magnetic Field Generated in a Switched Plasma

The effect of a magnetized transient plasma on a circularly polarized source wave, when the rise time of the electron density profile is comparable to the source wave period, is considered. The H-formulation Green's function is developed to study the effect of a finite rise time on the generation of a wiggler magnetic field.     

Two‐dimensional magnetosonic shock wave propagation in dense electron–positron–ion plasmas

Two‐dimensional (2D) magnetosonic wave propagation in magnetized quantum dissipative plasmas is studied. The plasma system is comprised of inertial ions, inertia‐less electrons, and positrons. The multi‐fluid quantum hydrodynamic model is used, in which quantum statistical and quantum tunnelling effects of electrons and positrons are included. Reductive perturbation analysis is performed to derive the Zabolotskaya–Khokhlov equation for the 2D propagation of a magnetosonic shock wave in a magnetized qauntum plasma. The effects of varying the different plasma parameters such as positron density and magnetic field intensity on the propagation characteristics of magnetosonic shock waves are discussed with non‐relativistic degenerate plasma parameters in astrophysical plasma situations.     

Propagation of circularly polarized waves in one-dimensional bragg structures (magnetophotonic crystals)

A theory of electromagnetic wave propagation in structures formed by alternating magnetic and dielectric layers is proposed. Models of macroscopically thick and atomically thin layers magnetized perpendicular to their plane are considered. Transfer matrices of circularly polarized waves and characteristics of light propagation in periodic magnetic structures under normal incidence are obtained by the self-consistent electrodynamic Green’s function method in analytic form. The results obtained are employed to analyze linear-in-magnetization magneto-optical effects in the transmittance and reflectance spectra of one-dimensional magnetic Bragg structures called magnetophotonic crystals. For structures of finite thickness, Faraday rotation and other observable magneto-optical quantities are shown to vary appreciably in the spectral region of the stop bands of a magnetophotonic crystal. This is paralleled by a substantial enhancement of the magnetic-fieldinduced modulation of the reflectance of light polarized in the analyzer plane.     

THz波在不同角度磁化的非均匀磁化等离子体中的传输特性分析

为利用太赫兹波解决飞行器再入过程遇到的“黑障”问题,以散射矩阵方法为基础,分别以非均匀磁化等离子体的磁化方向、电子密度、外加磁场强度和碰撞频率为变量,研究了垂直入射情形下它们对太赫兹波传输行为的影响.结果表明:这些参数对太赫兹波传输性能影响明显,例如按某一方向改变磁化角度对左极化和右极化太赫兹波的传输功率有相反的影响;降低磁化强度能一定程度地避开等离子体对右极化波的吸收;而降低碰撞频率能缩小等离子体对右极化波的吸收频带.通过调整这些参数,有望在一定程度上缓解黑障现象.     

Propagation of azimuthal waves along the surface of a metal current-carrying cylinder immersed into a magnetized plasma

It is shown that a metal current-carrying cylinder immersed into a cold magnetized plasma is a waveguide structure, in which coupled bulk ordinarily polarized and surface extraordinarily polarized waves can propagate along the azimuthal direction. Their interaction, stipulated by the fact that besides the longitudinal component, the external magnetic field has also a weak azimuthal component, is studied. Analytical expressions for the corrections to the eigenfrequency of these waves, stipulated by the effect of a constant azimuthal magnetic field, are obtained for the case of a uniform plasma density. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 2, pp. 122–135, February 2008.