弱纵向外电场对磁化等离子体中哨声波的影响

本文以等离子体动力论为基础讨论存在纵向外电场时磁化等离子体的哨声波。由于外电场的影响,等离子体偏离平衡态。取电子稳态分布函数为局域的麦克斯韦分布,用沿无扰轨道积分方法求出系统的介电张量,并分别用介电张量的厄米部份和反厄米部份分析哨声的色散关系和增长率。对于波矢在以电场方向为轴顶角为2c锥角范围内的哨声,外电场的作用使波增长;波矢在此锥角范围之外,外电场的作用使其衰减。波的增长率随频率增高而增大,随波矢倾角增大而减小。ee时,波矢与外电场平行对应的最大增长率与等离子体密度成正比,与磁场强度成反比。文中还给出了以电离层F层作背景参数的数值计算结果。     

EFFECT OF A WEAK LONGITUDINAL ELECTRIC FIELD ON WHISTLER WAVES

The effect of a longitudinal electric field on whistler waves is studied based onkinetic theory.A local Maxwellian distribution is taken as stationary distribution function ofelectrons which departs from thermodynamic equilibrium due to the applied electric field.Thedielectric tensor is derived by integrating along orbit of the particle in the unperturbed field.Dispersion relation and growth rate are analysed from Hermitian and anti-Hermitian parts ofthis tensor respectively.It is found that the waves are growing when the angle between the wavevector and the electric field is in range of θ<2θ_c, otherwise the whistler waves are damping.Thegrowth rate increases with wave frequency and decreases with the angle between the wave vectorand the applied field.In the case of ω_e(?)Ω the maximum of growth rate,which is at θ=O_l isproportional to the plasma density and anti-proportional to the magnetic field.Some computedresults for parameters at top of the F layer are given.     

Plasma Parameters in the Reactor with Simultaneous Magnetron Discharge and Inductive Radio-Frequency Discharge in the Presence of External Magnetic Field

A plasma reactor that contains vacuum–arc and magnetron sputtering sources and radio-frequency discharge that generates high-density plasma in the presence of external magnetic field is developed, constructed, and optimized. The reactor can be used for deposition of various functional coatings with ion stimulation. The parameters of the inductive radio-frequency discharge generated in the presence of external magnetic field that serves as a source of assisting ions are optimized. It is shown that the working interval of the induction of external magnetic field corresponds to the resonant excitation of the coupled helicon and Trivelpiece–Gold waves. The effect of magnitude and configuration of magnetic field on the parameters of gas-discharge plasma and ion current in the substrate region is studied in the presence of separately and simultaneously initiated magnetron and inductive discharges. The effect of ion flux that is incident on the films in the course of growth on the structure of functional coatings is analyzed.     

Radiation from a uniaxially anisotropic plasma half space

A line source of magnetic currents is located in a half space with uniaxially anisotropic dielectric constant, with the optic axis inclined at an arbitrary angle to the interface. This two-dimensional, scalar diffraction problem is solved by Fourier integral techniques, and the solution is examined in the asymptotic range of large distance from the source. The radiation field comprises incident, reflected and refracted ray contributions whose properties are determined from a study of the refractive index curves for the medium. In addition, there may exist a lateral wave which is excited by a critically refracted incident ray, and which sheds energy back into the anisotropic medium by refraction. If the medium is a plasma with an externally impressed infinite dc magnetic field, and if the source oscillates below the plasma frequency, there exist shadow regions from which the direct and reflected rays are excluded but which can be penetrated by the lateral waves.     

Propagation in Transversely Magnetized Compressible Plasma Between Two Parallel Planes

The propagation of waves in compressible single fluid macroscopic plasma between two parallel, perfectly conducting planes, with a transverse static magnetic field parallel to the boundaries is investigated. It is shown that the TE waves are not affected by either the static magnetic field or the compressibility of the plasma, while the TM wave will be affected by both.     

Plane Waves Propagating in Chiral Plasma and Chiral Ferrite Media

Plane wave propagation in chiral plasma and chiral ferrite media is studied in kDB coordinate system. General wave equations and characteristic equations of plane waves propagating along an arbitrary direction in chiral plasma and in chiral ferrites are derived in simple formulations respectively. Four wavenumbers and their corresponding dispersion characteristics are resulted for propagation both along and normal to the biasing magnetic field. When plane wave with negative helicity propagates along the biasing magnetic field in chiral ferrites, backward waves emerge. However backward waves occur with both positive and negative helicities when propagating along the biasing magnetic field in chiral plasma.     

Radiation from an electromagnetic source in a half-space of compressible plasma-surface waves

The radiation characteristics of a line source of magnetic current are studied for the case in which the source is situated in a half-space of isotropic, compressible plasma which is bounded on one side by a perfectly conducting, rigid plane screen. In addition to the electromagnetic and plasma space waves, the line source excites a boundary wave. This boundary wave is a coupled wave. It has associated with it both a magnetic field component and the pressure term. This is in contrast to the space waves which can be decomposed into an electromagnetic (EM) mode with no pressure term and a plasma (P) mode with no magnetic field associated with it. The characteristics of this boundary wave are evaluated. The boundary wave propagates for all frequencies and the power carried by the boundary wave becomes smaller as the frequency is increased.     

双层YIG波导中静磁体波的传播特性

本文研究了在倾斜静磁场作用下,双层YIG薄膜波导结构中静磁体波的传播特性,得到了其色散的特征方程,计算了磁场倾角从5°到20°范围内双层波导结构中静磁体波传播的色散关系和延迟特性.结果表明,斜向场情况下在双层YIG薄膜结构中传播的静磁体波适合应用于高频范围,并且通过调节磁场倾角可以获得比单层膜波导结构更好的延迟率可调范围.斜向场情况下采用双层YIG薄膜结构,对于改进静磁波器件和磁光波导器件的性能具有十分重要的意义.     

ECR等离子体沉积系统中等离子体特性的模拟

本文建立了一个物理模型，编写了数值程序，模拟了微波电子回旋共振（ＥＣＲ）等离子体流的特性。假定等离子体中的电子服从玻尔兹曼关系，离子在从共振区流向衬底的过程中与中性气体发生电荷交换和弹性碰撞。根据等离子体区应满足的电荷准中性条件，采用蒙特卡罗方法可计算出自恰的等离子体电位及离子密度分布。从而分析了磁场形态和气压对等离子体密度空间分布，入射到衬底上的离子通量和平均能量的影响，结果表明：磁场形态和气压都可用来独立控制等离子体流的性能，这对于使用该种等离子体源进行薄膜沉积和刻蚀有一定的理论指导意义。     

Surface Waves on an Anisotropic Plasma Sheath

A treatment of the excitation of unidirectional plane surface waves on a perfectly conducting screen covered with an anisotropic plasma sheath is given for the case in which the external magnetic field is oriented parallel to the screen but perpendicular to the direction of propagation. The dispersion relations for the surface waves and their dependence on the strength of the external magnetic field and the sheath thickness, are discussed. For sufficiently small sheath thickness, backward surface waves are found to exist. The powers carried by the surface waves and the space waves are evaluated, and the efficiency of excitation of the surface waves are determined as a function of sheath thickness for a typical set of parameters. The power carried by the forward and backward surface waves are compared for two cases in which, in a given direction, either one or both of these exist.     

Radiation of millimeter waves from a grooved ferrite image line

Radiation of millimeter waves from a grooved ferrite image line is investigated. The beam angle is found to shift 20° with the bias magnetic field up to 0.8 Wb/m²in the frequency region near 40 GHz, and nonreciprocal behavior of the beam angle is also confirmed.     

高密度螺旋波等离子体源的应用进展

首先介绍了螺旋波的定义、螺旋波等离子体源产生等离子体所需条件的工作范围以及螺旋波等离子体源主要的一些应用.按照所加磁场范围的不同(分为在磁感应强度为100～1 600 Gs和在强磁场中两部分),分别进一步讨论了国内外各研究小组研制的等离子体源的运行参数及技术特点.随后介绍了螺旋波等离子体源在刻蚀、薄膜沉积和火箭推进三个...     

Study of a longitudinally nonuniform plasma layer

Transformation of the energy of surface waves in a plane plasma layer with a longitudinal irregularity of density is studied by the method of spectral decomposition. The total field is represented by an expansion in surface and pseudo-surface waves. A system of integro-differential equation for the coefficients of expansion determining the amplitudes of the transmitted, reflected, and scattered waves is obtained. It is shown that, in some special cases, this system of equations is reduced to a system of ordinary differential equations even if the plasma density rapidly changes. The fraction of the energy of surface waves that transforms into radiation at an acute angle with the layer can reach 50–60%.     

On Radial Transmission Line Representations of Electromagnetic Fields in an Anisotropic Moving Medium

The problems of electromagnetic waves in moving isotropic or uniaxial mediums have been dealt with by numerous authors. Chawla and Unz considered the fields in a moving anisotropic plasma, and Chen and Cheng analyzed waves in an isotropic plasma in a moving dielectric medium. In this note we consider electromagnetic fields in a moving anisotropic medium and propose the network formulation of electromagnetic fields in the moving medium in the radial cylindrical coordinate. The method is an extension of the transmission line representation of electron beams on infinite magnetic fields. We can apply these results to the cases of any magnetic field intensity and, further, solve the complex problems for a stationary anisotropic plasma by a similar method.     

Radiation from a line source in a ground plane covered by a warm plasma slab

The problem of a magnetic line source in a ground plane coated with a warm plasma slab is investigated. Consideration is given to electromagnetic and plasma waves in the slab and to the coupling at the boundaries between these waves and the free-space fields. An integral expression for the radiation field is obtained and is evaluated by the method of steepest descent. The resulting radiation patterns display interesting effects due to electron pressure near the electron plasma frequency, and these are discussed with the help of the transmission line analog to the problem. The surface-wave poles are located and discussed using this same analog.     

Effective Length of a Receiving Antenna in a Streaming Plasma

The root-mean-square (r.m.s) voltage induced on a receiving dipole antenna by incident potential waves in a streaming otherwise isotropic plasma in the resonance frequency band is calculated. The open-circuit voltage on antenna terminals is the product of the wave electric field strength at the receiving point and the effective length of the receiving antenna$L_eff$. The effective length differs substantially from that in a non-streaming plasma for waves propagating downstream at frequencies close to the plasma frequency. The case of stream velocity lower than the electron thermal velocity is considered, which is of interest for wave measurements in the solar wind. We discuss some implications for relevant experiments in space plasmas, namely the appearance of narrowband lines in the spectra around local plasma frequency observed in the solar wind. The possible exaggeration of plasma wave amplitudes in conventional interpretations of measurements is pointed out.     

Electro-acoustic Lateral Waves in a Hot Plasma†

This paper considers the possibility of excitation of lateral waves in a compressible plasma in contact with conducting boundaries. The present investigation demonstrates the existence of a peculiar type of lateral wave which travels a certain distance along the conducting surface with the phase velocity of light in a cold plasma and is then reflected back at the critical angle into the compressible plasma in which the wave propagates with the phase velocity of acoustic waves. These electro-acoustic lateral waves ore the contribution to the pressure field integral from the integration around the branch cut which depends on both the velocity of light and the adiabatic sound velocity in plasma-electrons.     

Surface waves on a uniaxial plasma slab--Their group velocity and power flow

The relation between group velocity and the velocity of energy transport for surface waves in plane-stratified, anisotropic, dispersive media, which was derived in [1], is verified by direct calculation for the case of surface waves on a uniaxial, cold plasma slab located in free space. A superimposed dc magnetic field of infinite strength and parallel to the interfaces generates the uniaxial anisotropy in the slab. Surface waves having an arbitrary direction of propagation with respect to the dc magnetic field are considered. A useful graphical presentation of the dispersion relation is given, from which the direction of propagation of "surface wave rays" is directly obtained.     

Scattering of electromagnetic waves by an anisotropic plasma-coated conducting cylinder

This paper considers the scattering of electromagnetic waves by an infinitely long anisotropic plasma-coated conducting cylinder. The source is assumed to be a magnetic current filament which gives rise to an incident magnetic field with only an axial component. Complete expressions for the scattered electric and magnetic fields are obtained. Scattering by an anisotropic plasma column and that by an isotropic plasma-coated conducting cylinder are special cases of the present problem.     

Reflection coefficient of a semiconductor superlattice subjected to a magnetic field

Propagation of magnetoplasma waves in a structure formed by periodically alternating semiconductor and dielectric layers is studied for the case where an external magnetic field is applied parallel to the layers; the waves traveling in the plane normal to the field are considered. Dispersion characteristics are calculated with the finiteness of the speed of light accounted for, and the features of the structure reflectivity are analyzed. It is demonstrated that the physical parameters and thicknesses of the layers composing the superlattice can be obtained from the frequency, angle of incidence, and magnetic-field dependences of the reflection coefficient.