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1.
The nonlinear properties of electron acoustic waves in a magnetized plasma consisting of hot electrons, hot ions, and cold electrons are investigated. Using a fluid-guiding center model for the cold electrons and Boltzmann distributions for the hot species, a set of nonlinear mode-coupling equations is derived. Monopole and dipole-vortex solutions are shown to exist for the system of nonlinear equations. Spectrum cascade by mode-coupling in the electron acoustic wave turbulence is investigated. Relevance of our investigation to broadband electrostatic noise (BEN) in the geomagnetic tail is discussed. 相似文献
2.
E. K. El-Shewy M. I. Abo el Maaty H. G. Abdelwahed M. A. Elmessary 《Astrophysics and Space Science》2011,332(1):179-186
The nonlinear properties of small amplitude dust-acoustic solitary waves (DAWs) in a homogeneous unmagnetized plasma having
electrons, singly charged ions, hot and cold dust species with Boltzmann distributions for electrons and ions have been investigated.
A reductive perturbation method was employed to obtain the Kadomstev-Petviashvili (KP) equation. The effects of the presence
of charged hot and cold dust grains on the nature of DAWs were discussed. Moreover, the energy of two temperatures charged
dusty grains were computed. The present investigation can be of relevance to the electrostatic solitary structures observed
in various space plasma environments. 相似文献
3.
Investigation of nonlinear wave modulation of electron-acoustic solitary wave packets in planar as well as nonplanar geometry is carried out for an unmagnetized two temperature plasma composed of cold and hot (featuring q-nonextensive distribution) electrons with stationary ions. It is shown that in such plasma, propagation of EA wave packets is governed by a modified NLSE which accounts for the geometrical effect and the nonextensivity of the hot electron species. It is found that the nature of the modulational instabilities would be significantly modified due to the geometrical effects, density ratio α of the hot-to-cold electrons species as well as their temperature ratio θ. Also, there exists a modulation instability period for the cylindrical and spherical envelope excitations, which does not exist in the one-dimensional case. Furthermore, spherical EA solitary wave packets are more structurally stable to perturbations than the cylindrical ones. The relevance of the current study to EA wave modulation in auroral zone plasma is highlighted. 相似文献
4.
This paper investigates wave properties of hot plasma in a Veselago medium. For the Schwarzschild black hole, the 3+1 GRMHD
equations are re-formulated which are linearly perturbed and then Fourier analyzed for rotating (non-magnetized and magnetized)
plasmas. The graphs of wave vector, refractive index and change in refractive are used to discuss the wave properties. The
results obtained confirm the presence of Veselago medium for both rotating (non-magnetized and magnetized) plasmas. This work
generalized the isothermal plasma waves in the Veselago medium to hot plasma case. 相似文献
5.
S. K. El-Labany M. Shalaby R. Sabry L. S. El-Sherif 《Astrophysics and Space Science》2012,340(1):101-108
A theoretical investigation is carried out for understanding the properties of electron-acoustic potential structures (i.e.,
solitary waves and double-layers) in a magnetized plasma whose constituents are a cold magnetized electron fluid, hot electrons
obeying a nonthermal distribution, and stationary ions. For this purpose, the hydrodynamic equations for the cold magnetized
electron fluid, nonthermal electron density distribution, and the Poisson equation are used to derive the corresponding nonlinear
evolution equation; modified Zakharov–Kuznetsov (MZK) equation, in the small amplitude regime. The MZK equation is analyzed
to examine the existence regions of the solitary pulses and double-layers. It is found that rarefactive electron-acoustic
solitary waves and double-layers strongly depend on the density and temperature ratios of the hot-to-cold electron species
as well as the nonthermal electron parameter. 相似文献
6.
The nonlinear properties of solitary waves structure in a hot dusty plasma consisting of isothermal hot electrons, non isothermal
ions and high negatively charged massive dust grains, are reported. A modified Korteweg-de Vries equation (modified KdV),
which admits a solitary waves solution for small but finite amplitude, is derived using a reductive perturbation theory. A
nonisothermal ions distribution provides the possibility of coexistence of amplitude rarefactive as well as compressive solitary
waves. On the other hand, consideration of a critical ions density gives a stationary solution of solitary waves and the dynamics
of small but finite amplitude of solitary waves is governed by Korteweg-de Vries equation (KdV). The properties of solitary
waves in the two cases are discussed. 相似文献
7.
S. A. El-Wakil Essam M. Abulwafa E. K. El-Shewy Abeer A. Mahmoud 《Astrophysics and Space Science》2013,346(2):383-393
The reductive perturbation method has been used to derive the Burgers equation for dust acoustic shock waves in unmagnetized plasma having electrons, singly charged ions, hot and cold dust species with Boltzmann distributions for electrons and ions in the presence of the cold (hot) dust viscosity coefficients. The time-fractional Burgers equation is formulated using Euler-Lagrange variational technique and is solved using the variational-iteration method. The effect of time fractional parameter on the behavior of the shock waves in the dusty plasma has been investigated. 相似文献
8.
Large amplitude solitons are investigated in an electron-positron plasma consisting of a hot and cold component for each charged species. The existence (and amplitudes) of the solitons are studied as a function of plasma parameters such as particle number densities and temperatures. Both compressive and rarefactive solitons are found to occur. Possible applications to pulsar magnetospheres are discussed.Also attached to Plasma Physics Research Institute, University of Natal, Durban, South Africa. 相似文献
9.
Electron acoustic solitary waves in a collisionless plasma consisting of a cold electron fluid and non-thermal hot electrons are investigated by a direct analysis of the field equations. The Sagdeev potential is obtained in terms of electron acoustic speed by simply solving an algebraic equation. It is found that the amplitude and width of the electron acoustic solitary waves as well as the parametric regime where the solitons can exist are very sensitive to the population of energetic non-thermal hot electrons. The soliton and double layer solutions are obtained as a small-amplitude approximation. The effect of non-thermal hot electrons is found to significantly change the properties of the electron acoustic solitary waves (EAWs). A comparison with the Viking Satellite observations in the day side auroral zone is also discussed. 相似文献
10.
In this paper we examine the wave properties of a hot plasma living in a Schwarzschild magnetosphere. The 3+1 GRMHD perturbation
equations are formulated for this scenario. These equations are Fourier analyzed and then solved numerically to obtain the
dispersion relations for a non-rotating, rotating non-magnetized and rotating magnetized plasma. The wave vector is evaluated,
which is used to calculate the refractive index. These quantities are shown in graphs which are helpful to discuss the dispersive
properties of the medium near the event horizon. 相似文献
11.
Tomikazu Namikawa Hiromitsu Hamabata Yasusi Hosoya S. Matsushita 《Planetary and Space Science》1983,31(8):913-921
Propagation characteristics of hydromagnetic waves in a cold plasma mixed with a hot plasma under a uniform static magnetic field are investigated. The existence of cold plasma seriously affects the polarization properties of the waves. The results are applied to the interpretation of Pcl and Pc5 with righthand polarizations guided along the geomagnetic field line. 相似文献
12.
Nonlinear dynamics of electron acoustic waves (EAWs) in a plasma consisting of stationary ions, cool inertial electrons and hot electrons having a nonextensive distribution is studied. Under transverse perturbations, the nonlinear wave can be described by the general form of the Davey-Stewartson (DS) equations. The reductive perturbation technique is employed to derive Davey-Stewartson equations. From the solutions of these equations, amplitude modulation properties and stability regions of EAWs are studied in two-dimensional plasma. Further, the influence of nonextensivity of hot electrons (via q) on the characteristics of EAWs has been analysed. 相似文献
13.
The nonlinear properties of solitary waves structure in a hot magnetized dusty plasma consisting of a negatively charged,
extremely massive hot dust fluid, positively charged hot ion fluid and vortex-like distributed electrons, are reported. A
modified Korteweg de Vries equation (mKdV) which admits a solitary wave solution for small but finite amplitude is derived
using a reductive perturbation theory. The modifications in the amplitude and width of the solitary wave structures due to
the inclusion of an external magnetic field and dust and ions temperature are investigated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
L. V. Ksanfomality 《Solar System Research》2007,41(6):463-482
In this paper, we consider the physical properties and characteristic features of extrasolar planets and planetary systems, those, for which the passage of low-orbit giant planets across the stellar disk (transits) are observed. The paper is mostly a review. The peculiarities of the search for transits are briefly considered. The main attention in this paper is given to the difference in the physical properties of low-orbit giant planets. A comparison of the data obtained during the transits of “hot Jupiters” points to the probable existence of several distinct subtypes of low-orbit extrasolar planets. “Hot Jupiters” of low density (HD 209458b), “hot Jupiters” with massive cores composed of heavy elements (HD 149026b), and “very hot Jupiters” (HD 189733b) are bodies that probably fall into different categories of exoplanets. Dissipation of the atmospheres of low-orbit giant planets estimated from the experimental data is compared with the calculated Jeans atmospheric losses. For “hot Jupiters”, the expected Jeans mass losses due to atmospheric escape on a cosmogonic time scale hardly exceed a few percent. Low-orbit giant planets should have a strong magnetic field. Since the orbital velocity of “hot Jupiters” is close to the magnetosonic velocity (or can even exceed it), the moving planet should actively interact with the “stellar wind” plasma. The possession of a magnetic field by extrasolar planets and the effects of their interaction with plasma can be used to search for extrasolar planets. 相似文献
15.
A. N. Semena M. G. Revnivtsev I. M. Khamitov R. A. Burenin T. Ak Z. Eker M. N. Pavlinsky 《Astronomy Letters》2013,39(4):227-236
The properties of the hot zone in the accretion flow near the surface of a magnetized white dwarf have been studied. For this purpose, the aperiodic optical variability of LS Peg, one of the brightest intermediate polars in the northern sky, has been investigated. The main radiation of the hot zone, which is then reemitted in the optical band, results from the radiation of an optically thin plasma heated during the passage of the accretion flow of a standing shock. Recently, Semena and Revnivtsev (2012) have shown that the aperiodic variability (flickering) of accreting magnetized white dwarfs should have a characteristic feature in the range of Fourier frequencies corresponding to the plasma cooling time in this hot region. The photometric brightness measurements for LS Peg made with the RTT-150 telescope using a high-speed ANDOR iXon CCD array have allowed the break frequency in the power spectrum of the source’s variability to be constrained. Constraints on the geometry of the accretion column for the white dwarf in LS Peg and on the plasma parameters in it have been obtained. 相似文献
16.
S. K. El-Labany H. N. Abd El-Razek G. A. El-Gamish 《Astrophysics and Space Science》2014,353(2):413-416
The self-similar expansion method is applied on the fluid system of equations which describes a plasma system consisting of opposite polarity dust grains, positive ions and electrons. The resultant system of equations is solved numerically to study the properties of the plasma expansion of this system. It is found that the presence of the second species of the dust has a great effect on the properties of the expansion of the other species. 相似文献
17.
C. Rozina N. L. Tsintsadze M. Jamil A. Rasheed S. Ali 《Astrophysics and Space Science》2014,353(2):485-491
By employing the anisotropic plasma distribution function, the stability of circularly polarized electromagnetic (EM) waves is studied in a relativistically hot electron-positron-ion (e-p-i) plasma, investigating two specific scenarios. First, linear dispersion relations associated with the transverse EM waves are analyzed in different possible frequency regimes. The expression of the aperiodic hydrodynamic instability is obtained and numerically the transverse EM modes are shown to grow exponentially. Secondly, we have found that the transverse electromagnetic wave interact with a collisionless anisotropic e-p-i plasma and damp through the nonlinear Landau damping phenomena. Taking the effects of the latter into consideration, a kinetic nonlinear Schrödinger equation is derived with local and nonlocal nonlinearities, computing the damping rates. The present work should be helpful to understand the linear and nonlinear properties of the intense EM waves in hot relativistically astrophysical plasmas, e.g., pulsars, black holes, neutron stars, etc. 相似文献
18.
In the present investigation, Electron acoustic solitons in a plasma consisting of cold electrons, superthermal hot electrons and stationary ions are studied. The basic properties of small but finite amplitude solitary potential structures that may exist in a given plasma system have been investigated theoretically using reductive perturbation technique. It has been found that the profile of electron acoustic solitary wave structures is very sensitive to relative hot electron density, $\alpha(=\frac{n_{h0}}{n_{c0}})$ , temperature of hot to cold electrons, $\theta(=\frac{T_{h}}{T_{c}})$ and the spectral index κ. The implications of the present study may be applied to explain some features of large amplitude localized structures that may occur in the plasma sheet boundary layer. 相似文献
19.
A theoretical investigation has been performed on the nonlinear propagation of nonplanar (cylindrical and spherical) Gardner solitons (GSs) associated with the positron-acoustic (PA) waves in a four component plasma system consisting of nonthermal distributed electrons and hot positrons, mobile cold positrons, and immobile positive ions. The well-known reductive perturbation method has been employed to derive the modified Gardner (MG) equation. The basic features (viz. amplitude, polarity, speed, etc.) of nonplanar PA Gardner solitons (GSs) have been examined by the numerical analysis of the MG equation. It has been observed that the properties of the PA GSs in a nonplanar geometry differ from those in a planar geometry. It has been also investigated that the presence of nonthermal (Cairns distributed) electrons and hot positrons significantly modify the amplitude, polarity, speed, and thickness of such PA GSs. The results of our investigation should play an important role in understanding various interstellar space plasma environments as well as laboratory plasmas. 相似文献
20.
The linear and nonlinear properties of the modified electron thermal waves are studied. The waves are of acoustic nature and can exist without significant damping in a two-electron temperature plasma. Nonlinearly, they can form propagating localized regions with depletion of hot electrons. Practical applications of our results to space plasmas are discussed. 相似文献