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1.
将一类色散介质的介电常数写成有理分式函数形式,进而导出FDTD中电位移矢量D和电场强度E之间的关系,形成SO-FDTD方法. 应用该方法计算了冷等离子体平板对电磁波的反射系数,通过与解析结果的比较,验证了该算法的高效性和高精度,同时,应用SO-FDTD方法,计算了等离子体层对垂直入射电磁波的反射系数,结果表明:等离子体厚度、电子密度、电子密度的分布形式和入射波频率是影响反射系数的重要因素.
关键词:
等离子体
电磁波
FDTD方法 相似文献
2.
A. Chabchoub B. Kibler C. Finot G. Millot M. Onorato J.M. Dudley A.V. Babanin 《Annals of Physics》2015
The dynamics of waves in weakly nonlinear dispersive media can be described by the nonlinear Schrödinger equation (NLSE). An important feature of the equation is that it can be derived in a number of different physical contexts; therefore, analogies between different fields, such as for example fiber optics, water waves, plasma waves and Bose–Einstein condensates, can be established. Here, we investigate the similarities between wave propagation in optical Kerr media and water waves. In particular, we discuss the modulation instability (MI) in both media. In analogy to the water wave problem, we derive for Kerr-media the Benjamin–Feir index, i.e. a nondimensional parameter related to the probability of formation of rogue waves in incoherent wave trains. 相似文献
3.
《Physics letters. A》1987,123(6):276-282
We study analytically the interaction of the solitary waves of the regularized long-wave equation proposed by Peregrine and Benjamin et al. It is shown in the long-wave limit that the solitary waves interact inelastically, and that a new solitary wave as well as a radiation tail are generated as a result of the interaction. The result agrees with the numerical observation made by Bona et al. The analysis presented here can also be applied to the general weakly dispersive nonlinear wave systems, and it shows that the interaction property holds commonly for the nonintegrable systems. 相似文献
4.
A. V. Razin 《Radiophysics and Quantum Electronics》2006,49(7):520-534
We study excitation of acoustic, leaky, and surface waves by a time-harmonic force source located in a homogeneous isotropic
elastic half-space contacting a homogeneous gas. The force acts in the normal direction to the interface between the media.
We consider the case where the sound velocity in the gas is less than the velocity of the Rayleigh wave propagating along
the surface of the solid. An expression is derived for the period-averaged radiation power of the surface Stoneley wave. The
total radiation power is calculated for the acoustic wave in the gas and for the leaky pseudo-Rayleigh wave. Variations in
the radiation powers of the surface and leaky waves are analyzed as functions of the source depth. If the velocities of compressional
and shear waves in the elastic medium significantly exceed the sound velocity in the gas, then the radiation power of the
Stoneley wave turns out to be a factor of 106–108 smaller than the radiation powers of other waves. The radiation power of the Stoneley wave decreases monotonically with increasing
source depth, and the decrease becomes more pronounced with the increase in the difference between the acoustic impedances
of the contacting media. If the shear-wave velocity in the solid is close to the sound velocity in the gas, then the radiation
power of the Stoneley wave is comparable with the radiation powers of other waves and exhibits maximum at a certain source
depth. For some parameters of the gas and the solid, and for certain source depths, the Stoneley wave carries away more than
a half of the total radiation power. It is shown that, for certain relations between the parameters of the media, the radiation
power of the Stoneley wave increases due to redistribution of the radiated power from the pseudo-Rayleigh leaky wave. The
total power of these waves remains approximatly constant and, with accuracy of the order of 10−3, is equal to the radiation power of the Rayleigh wave at the vacuum-solid interface. It is shown that the acoustic-wave power
which can be transmitted to the upper layers of the atmosphere during an earthquake does not exceed 0.01% of the total power
radiated at a given frequency.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 7, pp. 577–592, July 2006. 相似文献
5.
Propagation and interaction of ion-acoustic solitary waves in a quantum electron-positron-ion plasma
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This paper discusses the existence of ion-acoustic solitary waves and their interaction in a dense quantum electron-positron-ion plasma by using the quantum hydrodynamic equations.The extended Poincar’e-Lighthill-Kuo perturbation method is used to derive the Korteweg-de Vries equations for quantum ion-acoustic solitary waves in this plasma.The effects of the ratio of positrons to ions unperturbation number density p and the quantum diffraction parameter H e (H p) on the newly formed wave during interaction,and the phase shift of the colliding solitary waves are studied.It is found that the interaction between two solitary waves fits linear superposition principle and these plasma parameters have significantly influence on the newly formed wave and phase shift of the colliding solitary waves.The investigations should be useful for understanding the propagation and interaction of ion-acoustic solitary waves in dense astrophysical plasmas (such as white dwarfs) as well as in intense laser-solid matter interaction experiments. 相似文献
6.
Narrowband localized wave packets that are nondispersing and nondiffracting in one transverse dimension are characterized in anomalously dispersive media by means of a Fourier approach. Depending on the group velocity, waves with a dispersion relationship characterized by real wavenumbers can be O or X waves, while we also find waves with evanescent wavenumbers. 相似文献
7.
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. 相似文献
8.
We study the effect of striction plasma density disturbances on the generation intensity of longitudional cold and plasma
oscillations due to polarization of the magnetic field-aligned ionospheric plasma irregularities with δNo<0 by a powerful radio wave. It is assumed that the plasma density level inside the irregularity intersects the upper-hybrid
resonance level, in the vicinity of which the cold oscillations excited directly by a powerful radio wave are transformed
to shorter-wave plasma oscillations. We consider the short plasma wave limit to reduce the problem to a system of two coupled
equations for the cold wave induction and plasma wave electric field. The first equation is supplemented by a local source
equal to the integral of the plasma wave electric field in the resonance region. The second equation involves the cold wave
induction at the resonance point and describes the electric field of interacting waves in the resonance vicinity. We use simplifications
connected with the small absorption of plasma waves propagating inside the irregularity and weak radiation of these waves
outside the irregularity. These conditions correspond to the generation of eigenmodes of plasma oscillations trapped in the
irregularity. We have obtained a resonance-type nonlinear equation for the electric field intensity (or energy flux) of eigenmode
plasma waves with allowance for striction disturbances of the plasma density profile in the resonance region. It is shown
that the striction expulsion of plasma is responsible for the occurrence of coefficients describing the change in the intensity
of excitation and radiation of plasma waves at the irregularity boundary. Such an expulsion leads to variations of the efficient
generation band of plasma eigenmodes with the total phase increment of the wave in the irregularity. It also leads to a change
in the phase shift of the plasma wave reflected from the resonance. These coefficients and the nonlinear phase shift are expressed
in terms of real wave functions of the nonlinear Airy equation which describes the electric field of the excited waves in
the resonance vicinity when the dissipation is absent.
Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, Troitsk, Moscow region,
Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 3, pp. 270–297, March, 1998. 相似文献
9.
A nonlinear Schrödinger equation for ion-acoustic waves in a collision free plasma, consisting of warm ions and hot isothermal electrons is derived using the KBM method. It is found that for finite ion temperature these waves are modulationally unstable only in a range of wave numbers. As the ratio of ion to electron temperature increases, the range of the unstable region decreases and shifts towards small wave numbers. 相似文献
10.
We ask about the possible existence of solitary waves in infinite, homogeneous, isotropic, elastic media. Namely, can a nonlinear localized wave packet propagate without altering its shape in such materials? We consider one- dimensional propagation both of body and surface waves. In the first case we show, under rather general assumptions, that if a wave packet propagates without altering its shape it must, of necessity, be a solution of a linear wave equation and in this sense, (body) solitary waves do not exist. Surface solitary waves may however exist: a model equation is derived in which nonlinear and dispersive effects balance each other to allow for waves-both periodic and solitary-of constant shape. It is conceivable they are of some relevance in seismology. 相似文献
11.
12.
We discuss a new phenomenon of the electrodynamics of transient media, the trapping of electromagnetic radiation by the boundary
of a transient plasma due to the conversion of the radiation into surface waves localized at the boundary. Calculations are
done for an initial plane wave and for a beam of finite width in conditions where the boundary of the suddenly created (because
of ionization) plasma half-space is perpendicular to the initial wavefront. Two frequency down-shifted surface waves traveling
along the boundary in opposite directions are shown to be excited, as well as frequency up-shifted outgoing radiation and
a time-independent mode in the form of a spatially inhomogeneous structure of dc currents and a magnetic field within the
plasma half-space. We study the associated kinematic, amplitude, and energy relations. Finally, we establish that the most
efficient trapping (up to 40% in energy) can be achieved with the forward (with respect to the direction of the initial wave
propagation) surface mode and that the trapping is accompanied by concentration of electromagnetic energy at the plasma boundary.
Zh. éksp. Teor. Fiz. 113, 1277–1288 (April 1998) 相似文献
13.
14.
Making use of the kinetic approach for plasma species, the electrostatic twisted dust-acoustic (DA) waves are studied in a collisionless unmagnetized multi-component dusty plasma consisting of electrons, singly ionized positive ions and charged massive dust grains. The Vlasov-Poisson equations are coupled together to obtain a generalized response function by using the Laguerre-Gaussian (LG) perturbed electrostatic potential and distribution function in the paraxial limit. The dispersive properties and growth rate instability of twisted DA waves are examined with distinct OAM states in a multi-component dusty plasma. Various significant modifications associated with the real wave frequency and growth rate are shown with respect to twist parameter and dust concentration. It is examined that dust concentration enhances the growth rate of twisted DA waves, whereas an increase in twist parameter reduces the growth rate instability. The excitation of twisted DA mode is also found to enhance with streaming speed of inertialess electrons. Our results may be useful for particle transport and trapping phenomena due to wave excitation in laboratory dusty plasmas. 相似文献
15.
In this paper we have theoretically investigated the quantum and relativistic effects on ion plasma wave in an unmagnetised dust-ion plasma. By using the method of normal mode analysis, we have obtained a linear dispersion relation. It has been analysed numerically for quantum and relativistic effects on the propagation of ion plasma wave. By using the standard reductive perturbation technique, we have derived a Korteweg–de Vries (KdV) equation which describes the nonlinear propagation of the wave. Numerically, it is shown that only compressive type of soliton can exist in the plasma under consideration. It is found that the solitary wave profile depends significantly on the quantum and relativistic parameters. The dust size, dust charge and the dust number density are also shown to have significant influences on these solitary waves. The results of this present investigation have some relevance to the nonlinear propagation of ion plasma wave in some astrophysical, space and laboratory plasma environments. 相似文献
16.
17.
We study theoretically the Vavilov-Čerenkov radiation from a nonrelativistic electron bunch moving in free space over a left-handed
medium. It is shown that in the frequency range in which the refractive index of the medium is negative, Vavilov-Čerenkov
radiation leads to simultaneous excitation of volume and surface electromagnetic waves in the same frequency range. The wave
vector of the surface wave in the plane of an interface of two media is greater in magnitude than the corresponding quantity
for the volume wave. The energy fluxes of volume and surface waves in the left-handed medium are studied. The radiation pattern
of the bunch is found.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 5, pp. 406–417, May 2007. 相似文献
18.
Kh. B. Tolipov 《Technical Physics》2012,57(9):1321-1324
We consider surface acoustic waves in an elastic wedge media. It is established that the investigated waves substantially differ from known ones. For example, the movement of surface Rayleigh wave in the direction to the edge leads to a change of its structure, accompanied by the splitting of the initial wave to two separate modes and radiation of shift and longitudinal waves. Along the edge of the wedge the surface wave is strongly localized in the transverse direction. Are discussed the properties of the wedge antisymmetric normal waves, propagating parallel to the edge of the wedge. 相似文献
19.
Linear and nonlinear ion acoustic waves are studied in unmagnetized electron-ion quantum plasmas. Sagdeev potential approach is employed to describe the nonlinear quantum ion acoustic waves. It is found that density dips structures are formed in the subsonic region in a electron-ion quantum plasma case. The amplitude of the nonlinear structures remains constant and the width is broadened with the increase in the quantization of the system. However, the nonlinear wave amplitude is reduced with the increase in the wave Mach number. The numerical results are also presented. 相似文献
20.
We investigate generation and radiation of waves at combined frequencies from an arbitrary inhomogeneous, isotropic plasma layer, when electromagnetic waves are obliquely incident on it to interact with a surface wave at the plasma boundary. This interaction has been described for both S- and P-polarized waves. We consider a warm plasma layer with thickness very small as compared to the wavelengths of oscillations. It is shown that generated waves are strongly amplified, compared to cold plasma, when phase velocities of generated waves approaches the electron thermal velocity. Waves are not emitted when P-polarized waves are incident perpendicular onto the plasma layer. 相似文献