Theory of Shear Alfven Vortex in Current-Carrying Plasma Plasma

Nonlinear shear Alfven waves in low P, current-carrying magnetized plasma are studied.Sets of nonlinear equations describing the shear Alfven waves are derived and corresponding dipolar vortex solutions are given for both regions of P, 0<β< m_e/m_i and m_e/m_i<<β<<1, respectively. Result shows that the equilibrium plasma current has remarkable effect on the behaviour of vortex motion. For the 0<β<< m_e/m_i case the current adds a low speed vortex propagating region in the opposite current direction, while for the < m_e/m_i<<β<<1 case the current reduces the region of vortex propagating speed by cutting a low speed region. The implication of this effect is discussed.     

Cold plasma dispersion relations in the vicinity of a Schwarzschild black hole horizon

We apply the ADM 3 + 1 formalism to derive the general relativistic magnetohydrodynamic equations for cold plasma in spatially flat Schwarzschild metric. Respective perturbed equations are linearized for non-magnetized and magnetized plasmas both in non-rotating and rotating backgrounds. These are then Fourier analyzed and the corresponding dispersion relations are obtained. These relations are discussed for the existence of waves with positive angular frequency in the region near the horizon. Our results support the fact that no information can be extracted from the Schwarzschild black hole. It is concluded that negative phase velocity propagates in the rotating background whether the black hole is rotating or non-rotating.     

等离子体柱中的短波漂移旋涡

本文研宄等离子体柱中短波漂移非线性波。我们推导出柱坐标系中描述该波的非线性耦合方程组,求出一类不同于在笛卡尔坐标系中得到的偶极旋涡(vortex)的新解。这类新解由轴对称和反对称两部分组成,称之为径向旋涡。     

Dispersion Relations for Cold Plasmas Around Reissner-Nordström Black Holes

We investigate the general relativistic magnetohydrodynamic (GRMHD) equations for cold plasma around the Reissner-Nordström black hole. Applying 3+1 spacetime split we linearize the perturbed equations for non-magnetized/magnetized plasma in both rotating and non-rotating background. By Fourier analyze we then derive dispersion relations and investigate the existence of waves with positive angular frequency in the vicinity of the black hole horizon. The analysis finds propagation of negative phase and group velocities for rotating magnetized surroundings.     

磁化等离子体中静电漂移波和剪切阿耳芬波的非线性耦合

本文采用Hasegawa-Wakatani方程组研究磁化等离子体中静电漂移波和剪切阿耳芬波的非线性耦合。求得非线性方程组的偶极涡旋解。这些解属于本性电磁涡旋,对应的扰动磁场和纵向电流在涡旋边界上是连续的。 关键词：     

非均匀磁化等离子体中的二维漂移孤波

本文导出了描述非均匀、磁化等离子体的非线性方程,找到了二维孤波解。它在结构上与文献所得到的解相似,但性质上有若干不同之处:此孤波解的传播速率可取零之外的任意值,而且可在垂直于磁场的平面内的任意方向传播;等离子体附着在孤波上而且随之一起横越磁场运动。这表明此种孤波解的存在与等离子体中横越磁场的反常输运现象是相关的。 关键词：     

Electromagnetic wave scattering from a magnetized plasma column including a thin annular magnetized relativistic rotating electron beam (TAMRREB)

The problem of the scattering of electromagnetic waves from a magnetized plasma column including a thin annular magnetized relativistic rotating electron beam is discussed theoretically. The backscattering cross-section and scattering pattern are presented for a transverse electric (TE) polarization. An investigation on the effects of system parameters on the backscattering cross-section and scattering pattern is done and the corresponding polarized charge density plots are presented.     

Nonlinear development of instabilities in supersonic vortex sheets: I. The basic kink modes

Classical linearized stability analysis predicts (neutral) stability of supersonic vortex sheets for compressible flow with normalized Mach numbers, M > √2, while recent detailed numerical simulations by Woodward indicate the nonlinear development of instabilities for M > √2 through the development and interaction of propagating kink modes in the slip-stream. These kink modes are discontinuities in the slip-stream bracked by shock waves and rarefaction waves which grow self-similarly in time. In this paper, the apparent paradox is resolved by developing appropriate small amplitude high frequency nonlinear time-dependent asymptotic perturbed solutions which yield the response to a very small amplitude nonlinear planar sound wave incident on the vortex sheet. The analysis leads to three specific angles of incidence depending on M > √2 where nonlinear resonance occurs. For these three special resonant angles of incidence the perturbation expansions automatically yield simplified equations. These equations involve an appropriate Hamilton-Jacobi equation for the perturbed vortex sheet location; the derivative of the solution of this Hamilton-Jacobi equation provides boundary data for two nonlinear Burgers transport equations for the sound wave emanating from the two sides of the vortex sheet. These equations are readily solved exactly and lead to the quantitative time-dependent nonlinear development of three different types of kink modes with a structure similar to that observed by Woodward.     

Electron exchange-correlation effects on dispersion properties of electrostatic waves in degenerate quantum plasmas

Based on the quantum Magnetohydrodynamic (QMHD) model, the obliquely propagation of electrostatic waves in degenerate magnetized quantum plasmas with electron exchange-correlation effects are theoretically investigated. The modified linear dispersion relations of electrostatic waves are obtained and discussed in some specific cases. The analytical results clearly show that the dispersion properties of the high frequency electron waves (including the Langmuir wave and upper-hybrid wave) and the low frequency ion acoustic wave are modified by the quantum effects together with the electron exchange-correlation effects. The numerical results depict that the Langmuir wave and upper-hybrid wave can be unstable in the presence of the electron exchange-correlation effects, and it is also evidently indicated that the electron exchange-correlation effects can reduce the phase velocity of the waves, especially in the high wave number region. The corresponding results should be of relevance for identifying electrostatic fluctuations which transport in an inhomogeneous and magnetized quantum plasmas.     

Stimulated Scattering from Ion Cyclotron Wave

A study is made of the stimulated backscattering of electromagnetic ordinary waves from obliquely propagating ion cyclotron waves in a magnetized plasma. It is found that the threshold is considerably lower and the growth rate considerably larger than the corresponding values for backscattering from perpendicularly propagating lower and upper hybrid waves.     

Vortex stretching as a mechanism for quantum kinetic energy decay

A pair of perturbed antiparallel quantum vortices, simulated using the three-dimensional Gross-Pitaevskii equations, is shown to be unstable to vortex stretching. This results in kinetic energy K(?ψ) being converted into interaction energy E(I) and eventually local kinetic energy depletion that is similar to energy decay in a classical fluid, even though the governing equations are Hamiltonian and energy conserving. The intermediate stages include the generation of vortex waves, their deepening, multiple reconnections, the emission of vortex rings and phonons, and the creation of an approximately -5/3 kinetic energy spectrum at high wave numbers. All of the wave generation and reconnection steps follow from interactions between the two original vortices. A four vortex example is given to demonstrate that some of these steps might be general.     

Intrinsic resonances in double layers with finite thickness

Short wavelength electrostatic perturbations in one-dimensional magnetized double layers are studied in the local WKB approximation. The corresponding dielectric function shows resonant interaction between fluctuations and electrons whose time of flight across the double layer is an integer multiple of the half period of waves.     

Solitary Waves of a Perturbed sine—Gordon Equation

Based on the bifurcation and the idea that the solitary waves and shock waves of partial differential equations correspond respectively to the homoclinic and heteroclinic trajectories of nonlinear ordinary differential equations satisfied by the travelling waves,different conditions for the existence of solitary waves of a perturbed sine-Gordon equation are obtained.All of the corresponding approximate solitary wave solutions are given by integrating the derived approximate equations directly.     

Effects of Schwarzschild black hole horizon on isothermal plasma wave dispersion

The 3 + 1 GRMHD equations for Schwarzschild spacetime in Rindler coordinates with isothermal state of plasma are formulated. We consider the cases of non-rotating and rotating backgrounds with non-magnetized and magnetized plasmas. For these cases, the perturbed form of these equations are linearized and Fourier analyzed by introducing plane wave type solutions. The determinant of these equations in each case leads to two dispersion relations which give value of the wave number k. Using the wave number, we obtain information like phase and group velocities etc. which help to discuss the nature of the waves and their characteristics. These provide interesting information about the black hole magnetosphere near the horizon. There are cases of normal and anomalous dispersion. We find a case of normal dispersion of waves when the plasma admits the properties of Veselago medium. Our results agree with those of Mackay et al. according to which rotation of a black hole is required for negative phase velocity propagation.     

Spontaneous thermal waves in a magnetized plasma

Coherent temperature oscillations corresponding to thermal (diffusion) waves are observed to be spontaneously excited in a narrow temperature filament embedded in a large, but colder, magnetized plasma. The parallel and transverse propagation properties of the waves satisfy the predictions of the classical transport theory based on Coulomb collisions. The frequency of the oscillations meets the conditions for a quarter-wave thermal resonator. This is the plasma version of thermal resonators used in the study of other states of matter.     

Numerical study of acoustic radiation dynamics of a Rankine vortex

The paper continues investigations of a fundamental problem important for understanding the nature of vortex flows: sound radiation by a perturbed Rankine vortex. Results of numerical simulation are presented for both quadrupole and higher-mode radiations. The structure and dynamics of tonal acoustic radiation generated by a vortex are considered in detail. The transition of a Rankine vortex to a perturbed state under small external perturbation is considered. Calculations are performed using the EBR scheme implemented by NOISEtte software.     

Effects of External Magnetic Field on Propagation of Electromagnetic Wave in Uniform Magnetized Plasma Slabs

Absorbers and reflectors of electromagnetic waves have many applications, and so the interactions between electromagnetic waves and low-temperature plasma, particularly numerical analysis of reflection, absorption, and transmission of electromagnetic waves in unmagnetized, magnetized, nonuniform, and uniform plasma, have been a topic of intensive research. For instance, Laroussi numerically evaluated the interactions between electromagnetic waves and a uniform magnetized plasma cylinder, and Helaly and Yeh studied the scattering from nonuniform magnetized plasma cylinders.     

Electromagnetic envelope solitons in magnetized plasma

A multiple scales technique is employed to solve the fluid-Maxwell equations describing a weakly nonlinear circularly polarized electromagnetic pulse in magnetized plasma. A nonlinear Schrödinger-type (NLS) equation is shown to govern the amplitude of the vector potential. The conditions for modulational instability and for the existence of various types of localized envelope modes are investigated in terms of relevant parameters. Right-hand circularly polarized (RCP) waves are shown to be modulationally unstable regardless of the value of the ambient magnetic field and propagate as bright-type solitons. The same is true for left-hand circularly polarized (LCP) waves in a weakly to moderately magnetized plasma. In other parameter regions, LCP waves are stable in strongly magnetized plasmas and may propagate as dark-type solitons (electric field holes). The evolution of envelope solitons is analyzed numerically, and it is shown that solitons propagate in magnetized plasma without any essential change in amplitude and shape.     

Electromagnetic Waves in Waveguide Partially Filled with Semiconductor Plasma

The dispersion of electromagnetic waves in waveguides partially filled with semiconductor plasma is investigated for unmagnetized and for strongly magnetized plasma. The effects which may be useful for the plasma electronics are found: In such waveguides there exist a large number of slow waves with typical frequencies ω ≈ ωP/√?_L. The filling at which the different modes at fixed phase velocity are maximum separated in wavelength is found. The thickness of the semiconductor layer at which this effect arises is about hundred micrometers and depends on the crystals' type. In addition to this, in strongly magnetized semiconductor plasma the maximum frequency separation of the typical plasma waves is found at fixed filling. Is it shown that in such systems there exist many surface waves which are of the slow wave type. In the case of strongly magnetized plasma coupling between nonsymmetrical EH- and HE- modes is shown to exist.     

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利用数值方法研究了双温离子、磁场、非均匀性和波的斜向传播对三维非线性尘埃声孤波振幅和宽度的影响。运用约化摄动法得到描述三维非线性尘埃声孤波的非标准变系数Korteweg-de Vries(KdV)方程。然后把非标准变系数KdV方程变为标准变系数KdV方程,并且得到了此标准变系数KdV方程的近似解析解。研究结果表明,此系统中存在着两种形式的孤波,即压缩型孤波和稀疏型孤波,外部磁场对三维非线性尘埃声孤波的宽度有影响,而对其振幅没有影响。此外,波的相速度与波的斜向传播和非均匀性有着非常紧密的联系。