共查询到20条相似文献，搜索用时 31 毫秒
1.
Nonlinear dynamics of electron-acoustic solitary waves in a magnetized plasma whose constituents are cold magnetized electron fluid, hot electrons featuring Tsallis distribution, and stationary ions are examined. The nonlinear evolution equation (i.e., Zakharov–Kuznetsov (ZK) equation), governing the propagation of EAS waves in such plasma is derived and investigated analytically and numerically, for parameter regimes relevant to the dayside auroral zone. It is revealed that the amplitude, strength and nature of the nonlinear EAS waves are extremely sensitive to the degree of the hot electron nonextensivity. Furthermore, the obtained results are in good agreement with the observations made by the Viking satellite. 相似文献
2.
Nonlinear electron-acoustic solitary waves (EASWs) are studied using Sagdeev’s pseudo-potential technique in a collisionless
unmagnetized plasma consisting of a cold electron fluid, nonthermal hot electrons and stationary ions. It is shown that the
presence of fast nonthermal electrons may modify the parametric region where electron-acoustic solitons may exist. Our investigation
is of wide relevance to astronomers and space scientists working on interstellar space plasmas. 相似文献
3.
S. K. El-Labany R. Sabry W. M. Moslem E. A. Elghmaz 《Astrophysics and Space Science》2014,349(2):773-780
Generation of quasielastic electron-acoustic (EA) waves head-on collision are investigated in non-planar (cylindrical/spherical) plasma composed of cold electrons fluid, hot electrons obeying nonthermal distribution, and stationary ions. The cylindrical/spherical Korteweg-de Vries (KdV) equations describing two bidirectional EA waves are derived and solved analytically. Numerical investigation have shown that only positive electron-acoustic (EA) structures can propagate and collide. The analytical phase shift |Δ A | due to the non-Maxwellian (nonthermal) electrons is different from the Maxwellian case. Both the hot-to-cold electron number density ratio α and nonthermal parameter β have opposite effect on the phase shift behavior. The phase shift of the spherical EA waves is smaller than the cylindrical case, which indicates that the former is more stable for collision. The relevance of the present study to EA waves propagating in the Earth’s auroral zone is highlighted. 相似文献
4.
Properties of fully nonlinear electron-acoustic solitary waves in an unmagnetized and collisionless electron-positron-ion plasma containing cold dynamical electrons, superthermal electrons and positrons obeying Cairns’ distribution have been analyzed in the stationary background of massive positive ions. A linear dispersion relation has been derived, from which it is found that even in the absence of superthermal electrons, the superthermal positron component can provide the restoring force to the cold inertial electrons to excite electron-acoustic waves. Moreover, superthermal electron and positron populations seem to enhance the electron acoustic wave phase speed. For nonlinear analysis, Korteweg-de Vries equation is obtained using the reductive perturbation technique. It is found that in the presence of positron both hump and dip type solitons appear to excite. The present work may be employed to explore and to understand the formation of electron acoustic soliton structures in the space and laboratory plasmas with nonthermal electrons and positrons. 相似文献
5.
Electron-acoustic solitary structures in two-electron-temperature plasma with superthermal electrons
The propagation of nonlinear electron-acoustic waves (EAWs) in an unmagnetized collisionless plasma system consisting of a
cold electron fluid, superthermal hot electrons and stationary ions is investigated. A reductive perturbation method is employed
to obtain a modified Korteweg–de Vries (mKdV) equation for the first-order potential. The small amplitude electron-acoustic
solitary wave, e.g., soliton and double layer (DL) solutions are presented, and the effects of superthermal electrons on the
nature of the solitons are also discussed. But the results shows that the weak stationary EA DLs cannot be supported by the
present model. 相似文献
6.
Sayed A. El-Wakil Essam M. Abulwafa Emad K. El-shewy Abeer A. Mahmoud 《Astrophysics and Space Science》2011,333(1):269-276
The time fractional KdV equation is derived for small but finite amplitude electron-acoustic solitary waves in plasma of cold
electron fluid with two different temperature isothermal ions. The effects of the time fractional parameter on the electrostatic
solitary structures are presented. It is shown that the effect of time fractional parameter can be used to modify the amplitude
of the electrostatic waves (viz. the amplitude, width and electric field) of the electron-acoustic solitary waves. The model
may provide a possible explanation for the low-frequency component of the broadband electrostatic noise in the plasma sheet
boundary layer of the Earth’s magnetotail where the electron beams are not present. 相似文献
7.
Propagation of cylindrical and spherical electron-acoustic solitary waves in unmagnetized plasmas consisting of cold electron
fluid, hot electrons obeying a superthermal distribution and stationary ions are investigated. The standard reductive perturbation
method is employed to derive the cylindrical/spherical Korteweg-de-Vries equation which governs the dynamics of electron-acoustic
solitons. The effects of nonplanar geometry and superthermal hot electrons on the behavior of cylindrical and spherical electron
acoustic soliton and its structure are also studied using numerical simulations. 相似文献
8.
H. G. Abdelwahed 《Astrophysics and Space Science》2012,341(2):491-500
Using the Viking Satellite observations data in the dayside auroral zone, a theoretical investigation is carried out for contribution of the higher-order nonlinearity to nonlinear obliquely electron-acoustic solitary waves (EASWs) in a magnetized collisionless plasma consisting of a cold electron fluid and non-thermal hot electrons obeying a non-thermal distribution, and stationary ions. A Zakharov–Kuznetsov (ZK) equation that contains the lowest-order nonlinearity and dispersion is derived from the lowest order of perturbation and a linear inhomogeneous (ZK-type) equation that accounts for the higher-order nonlinearity and dispersion is obtained. A stationary solution for equations resulting from higher-order perturbation theory has been found using the renormalization method. The effects of the external magnetic field and the obliqueness are found to significantly change the higher-order properties (viz. the amplitude, width, electric field and energy) of the EASWs. The effect of higher-order nonlinearity on the amplitude and width of the soliton are also discussed. A comparison with the Viking Satellite observations in the dayside auroral zone are taken into account. 相似文献
9.
Parvin Eslami Marzieh Mottaghizadeh Hamid Reza Pakzad 《Astrophysics and Space Science》2012,338(2):271-278
The head-on collision between two electron-acoustic solitary waves (EASWs) in an unmagnetized plasma is investigated, including
a cold electrons fluid, hot electrons, obeying a nonextensive distribution and stationary ions. By using the extended Poincaré-Lighthill–Kuo
(PLK) perturbation method, the analytical phase shifts following the head-on collision are derived. The effects of the ratio
of the number density of hot electrons to the number density of cold electrons α, and the nonextensive parameter q on the phase shifts are studied. It is found that q and the hot-to-cold electron density ratio significantly modify the phase shifts. 相似文献
10.
A theoretical investigation is made on the formation as well as basic properties of dust-ion-acoustic (DIA) shock waves in a magnetized nonthermal dusty plasma consisting of immobile charge fluctuating dust, inertial ion fluid and nonthermal electrons. The reductive perturbation method is employed to derive the Korteweg-de Vries-Burgers equation governing the DIA shock waves. The combined effects of external static magnetic field, obliqueness, nonthermal electron distribution and dust charge fluctuation on the DIA shock waves are also investigated. It is shown that the dust charge fluctuation is a source of dissipation, and is responsible for the formation of the DIA shock waves. It is also observed that the combined effects of obliqueness, nonthermal electron distribution and dust charge fluctuation significantly modify the basic properties of the DIA shock waves. The implications of our results in space and laboratory dusty plasma situations are briefly discussed. 相似文献
11.
A theoretical investigation has been made on obliquely propagating dust-ion-acoustic solitary waves (DIASWs) in magnetized
dusty electronegative plasma containing Boltzmann electrons, trapped negative ions, cold mobile positive ions, and arbitrarily
charged stationary dust. The reductive perturbation method has been employed to derive the modified Zakharov-Kuznetsov (MZK)
equation which admits solitary wave solution under certain conditions. The multi-dimensional instability of these solitary
waves is also studied by the small-k (long wavelength plane wave) perturbation-expansion technique. The basic properties (speed, amplitude, width, instability,
etc.) of small but finite amplitude DIASWs are significantly modified by the effects of external magnetic field, obliqueness,
polarity of dust, and trapped negative ions. The implications of our results in space and laboratory plasmas are briefly discussed. 相似文献
12.
S. A. Elwakil A. M. El-hanbaly E. K. El-Shewy I. S. El-Kamash 《Astrophysics and Space Science》2014,349(1):197-203
The nonlinear properties of small amplitude electron-acoustic solitary waves (EAWs) in a homogeneous system of unmagnetized collisionless plasma consisted of a cold electron fluid and isothermal ions with two different temperatures obeying Boltzmann type distributions have been investigated. A reductive perturbation method was employed to obtain the Kadomstev-Petviashvili (KP) equation. At the critical ion density, the KP equation is not appropriate for describing the system. Hence, a new set of stretched coordinates is considered to derive the modified KP equation. Moreover, the solitary solution, soliton energy and the associated electric field at the critical ion density were computed. The present investigation can be of relevance to the electrostatic solitary structures observed in various space plasma environments, such as Earth’s magnetotail region. 相似文献
13.
N. R. Kundu M. M. Masud K. S. Ashrafi A. A. Mamun 《Astrophysics and Space Science》2013,343(1):279-287
A rigorous theoretical investigation has been made on multi-dimensional instability of obliquely propagating electrostatic dust-ion-acoustic (DIA) solitary structures in a magnetized dusty electronegative plasma which consists of Boltzmann electrons, nonthermal negative ions, cold mobile positive ions, and arbitrarily charged stationary dust. The Zakharov-Kuznetsov (ZK) equation is derived by the reductive perturbation method, and its solitary wave solution is analyzed for the study of the DIA solitary structures, which are found to exist in such a dusty plasma. The multi-dimensional instability of these solitary structures is also studied by the small-k (long wave-length plane wave) perturbation expansion technique. The combined effects of the external magnetic field, obliqueness, and nonthermal distribution of negative ions, which are found to significantly modify the basic properties of small but finite-amplitude DIA solitary waves, are examined. The external magnetic field and the propagation directions of both the nonlinear waves and their perturbation modes are found to play a very important role in changing the instability criterion and the growth rate of the unstable DIA solitary waves. The basic features (viz. speed, amplitude, width, instability, etc.) and the underlying physics of the DIA solitary waves, which are relevant to many astrophysical situations (especially, auroral plasma, Saturn’s E-ring and F-ring, Halley’s comet, etc.) and laboratory dusty plasma situations, are briefly discussed. 相似文献
14.
Electron-acoustic waves are studied with orbital angular momentum (OAM) in an unmagnetized collisionless uniform plasma, whose constituents are the Boltzmann hot electrons, inertial cold electrons and stationary ions. For this purpose, we employ the fluid equations to obtain a paraxial equation in terms of cold electron density perturbations, which admits both the Gaussian and Laguerre–Gaussian (LG) beam solutions. Furthermore, an approximate solution for the electrostatic potential problem is found, which also allows us to express the components of the electric field in terms of LG potential perturbations. Calculating the energy flux of the electron-acoustic waves, an OAM density for these waves is obtained. Numerically, it is found that the parameters, such as, azimuthal angle, radial and angular mode numbers, and the beam waist strongly modify the LG potential profiles associated with electron-acoustic waves. The present results should be helpful to study the trapping and transportation of plasma particles and energy as well as to understand the electron-acoustic mode excitations produced by the Raman backscattering of laser beams in a uniform plasma. 相似文献
15.
Jiu-Ning Han Wen-Shan Duan Jun-Xiu Li Guang-Xing Dong Su-Hong Ge 《Astrophysics and Space Science》2014,351(2):525-531
A theoretical investigation has been made on the head-on collision of cylindrical and spherical electron-acoustic solitary waves in a non-Maxwellian plasma composed of stationary ions, cold fluid electrons, and superthermal electrons obeying κ velocity distribution. By using the extended Poincaré-Lighthill-Kuo perturbation method, the effects of plasma parameters, especially the superthermal effect on the interaction of colliding solitary waves are studied. It is found that there are both positive and negative colliding phase shifts for each colliding wave in its traveling direction. Also, it is shown that the solitary waves received the largest colliding phase shifts in spherical geometry, followed by the cylindrical and planar geometries. 相似文献
16.
A.A. Mamun 《Astrophysics and Space Science》1998,260(4):507-514
A rigorous theoretical investigation has been made of obliquely propagating dust-acoustic solitary structures in a cold magnetized two-ion-temperature dusty plasma consisting of a negatively charged, extremely massive, cold dust fluid and ions of two different temperatures. The reductive perturbation method has been employed to derive the Korteweg-de Vries (K-dV) equation which admits a solitary wave solution for small but finite amplitude limit. It has been shown that the presence of second component of ions modifies the nature of dust-acoustic solitary structures and may allow rarefactive dust-acoustic solitary waves (solitary waves with density dip) to exist in such a dusty plasma system. The effects of obliqueness and external magnetic field on the properties of these dust-acoustic solitary structures are also briefly discussed. 相似文献
17.
A theoretical investigation is carried out to analyse the propagation of ion acoustic (IA) waves in a magnetized bi-ion plasma having two populations of fluid ions and kappa-distributed electrons. The propagation properties of all possible modes (in the linear regime) are investigated. The nonlinear evolution of the IA solitary waves is governed by a Korteweg-de Vries (KdV)-like equation. The influence of obliqueness, magnitude of the magnetic field, ion polarity and electron superthermality on the IA waves is then examined. Our findings should aid in understanding the nonlinear electrostatic excitations that may propagate in spatial magnetized plasmas. 相似文献
18.
Arbitrary amplitude electron acoustic (EA) solitary waves in a magnetized nonextensive plasma comprising of cool fluid electrons, hot nonextensive electrons, and immobile ions are investigated. The linear dispersion properties of EA waves are discussed. We find that the electron nonextensivity reduces the phase velocities of both modes in the linear regime: similarly the nonextensive electron population leads to decrease of the EA wave frequency. The Sagdeev pseudopotential analysis shows that an energy-like equation describes the nonlinear evolution of EA solitary waves in the present model. The effects of the obliqueness, electron nonextensivity, hot electron temperature, and electron population are incorporated in the study of the existence domain of solitary waves and the soliton characteristics. It is shown that the boundary values of the permitted Mach number decreases with the nonextensive electron population, as well as with the electron nonextensivity index, q. It is also found that an increase in the electron nonextensivity index results in an increase of the soliton amplitude. A comparison with the Vikong Satellite observations in the dayside auroral zone is also taken into account. 相似文献
19.
Dust acoustic (DA) solitary wave existence conditions are investigated for positively charged dust particles in the presence
of nonthermal electrons. Once Sagdeev pseudo-potential derived through fluid equations, for large amplitude DA waves, the
lower limit on Mach number is calculated analytically using the necessary condition for the solitary waves existence. The
double layers conditions provides the upper limit on Mach number. This allowed us to numerically investigate the effect of
the temperature, density and nonthermal parameters on the solitary waves’ characteristics. The present study is devoted to
a complex plasma subject to ultraviolet radiations such as the one in the lower earth’s ionosphere. 相似文献
20.
The problem of arbitrary amplitude electron-acoustic solitary (EAS) waves in a plasma having cold fluid electrons, hot superthermal electrons and stationary ions is addressed. The domain of their allowable Mach numbers enlarges as the spectral index κ increases revealing therefore that the “maxwellisation” process of the hot component favors the propagation of the EAS waves. As the superthermal character of the plasma is increased, the potential pulse amplitude increases while its width is narrowed, i.e, the superthermal effects makes the electron-acoustic solitary structure more spiky. As the spectral index κ decreases, the hot electrons are locally expelled and pushed out of the region of the soliton’s localization. A decrease of the fractional number density of the hot electrons relative to that of the cold ones number density would lead to an increase of the depth as well as the width of the localized EAS wave. Our results should help to understand the salient features of large amplitude localized structures that may occur in the plasma sheet boundary layer and may provide an explanation for the strong spiky waveforms that have been observed in auroral electric fields. 相似文献