共查询到20条相似文献，搜索用时 31 毫秒
1.
S. A. Elwakil A. Elgarayhi E. K. El-Shewy Abeer A. Mahmoud M. A. El-Attafi 《Astrophysics and Space Science》2013,343(2):661-666
Effect of nonthermality of ions on the propagation of dust-acoustic waves (DAWs) in unmagnetized plasma having electrons, singly charged ions, hot and cold dust grains have been investigated. The reductive perturbation method is employed to reduce the basic set of fluid equations to the Korteweg-de Vries (KdV) equation. 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
2.
A theoretical investigation has been made of electrostatic solitary structures in an electron-positron-ion (e-p-i) plasma, taking nonextensive electrons and nonextensive positrons. By employing the reductive perturbation method, the basic characteristics of ion-acoustic (IA) solitary waves (SWs) in a three-component e-p-i plasma (consisting of negatively charged nonextensive electrons, positively charged nonextensive positrons, and ions) have been addressed. The Korteweg-de Vries (K-dV), modified K-dV (mK-dV), and Gardner equations are derived and their numerical solutions are obtained. It has been shown that the combined effects of electron nonextensivity, positron nonextensivity, and ions significantly modify the behavior of these electrostatic solitary structures that have been found to exist with positive and negative potential in this plasma model. The present analysis may be useful to understand and demonstrate the dynamical properties of IA SWs in different astrophysical and cosmological scenarios (viz. stellar polytropes, hadronic matter and quark-gluon plasma, protoneutron stars, dark-matter halos, etc.). 相似文献
3.
Our objective here is to investigate a strongly coupled dusty plasma system with the presence of polarization force (PF). This plasma consists of superthermal electrons, Maxwellian ions, and negatively charged dust grains. The nonlinear propagation of dust-acoustic (DA) waves in such dusty plasma system has been theoretically investigated by employing the reductive perturbation method. The Burgers’ and K-dV equations have been derived to and numerically analyzed. It has been found that the dust-acoustic shock and solitary waves exist associated with a negative potential only, and that the effect of the dust fluid temperature significantly modifies the basic properties (amplitude and width) of such nonlinear waves’ potential structures. We hope that the results of our present investigation should help us in understanding the localized electrostatic disturbances in space and laboratory strongly coupled dusty plasmas with superthermal electrons and polarization force. 相似文献
4.
太阳系尘埃等离子体研究 总被引：1，自引：0，他引：1
综述了太阳系尘埃等离子体中的充电机制和波动过程以及与之有关的若干空间物理现象,内容包括太阳系等离子体中尘埃表面的平衡电势,带电尘埃在空间环境中的受力与运动,行星环内沿的弥漫扩散,轮辐结构的成困,彗星环境中尘埃的静电爆裂,尘埃彗尾的形态演化,天王星窄环的稳定性等问题． 相似文献
5.
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
6.
Understanding the formation and evolution of the soil and dust of the Moon addresses the fundamental question of the interactions of space with the surface of an airless body. The physical and chemical properties of the lunar dust, the <20 μm portion of lunar soil, are key properties necessary for studies of the toxicity and the electrostatic charging of the dust. These properties have been largely overlooked until recent years. Although chemical and physical studies of the <20 μm portion of lunar soil have been the topic of several studies, there is still need for further studies, primarily of the <1 μm particles. This paper presents a review of the studies of lunar dust that have been conducted to date. As many preparations for future exploration or science activities on the Moon require testing using lunar soil/dust simulants, we also include a brief review of past and current simulants. 相似文献
7.
Properties of fully nonlinear ion-acoustic solitary waves in an unmagnetized and collisionless pair-ion (PI) plasma containing superthermal electrons obeying Cairns distribution have been analyzed. A linear biquadratic dispersion relation has been derived, which yields the fast (supersonic) and slow (subsonic) modes in a pair-ion-electron plasma with nonthermal electrons. For nonlinear analysis, Korteweg-de Vries equation is obtained using the reductive perturbation technique. It is found that in case of slow mode, both electrostatic hump and dip type structures are formed depending on the temperature difference between positively and negatively charged ions, whereas, only dip type solitary structures have been observed for fast mode. The present work may be employed to explore and to understand the formation of solitary structures in the space (especially, the Earth’s ionosphere where two distinct pair ion species (H ±) are present) and laboratory produced pair-ion plasmas with nonthermal electrons. 相似文献
8.
H. Alinejad 《Astrophysics and Space Science》2010,327(1):131-137
A theoretical investigation of the one dimensional dynamics of nonlinear electrostatic dust ion-acoustic (DIA) waves in an
unmagnetized dusty plasma consisting of ion fluid, non-thermal electrons and fluctuating immobile dust particles has been
made by the reductive perturbation technique. The basic features of DIA solitary and shock waves are studied by deriving the
Korteweg-de Vries (KdV) and KdV Burger equations, respectively. It is shown that the special patterns of nonlinear electrostatic
waves are significantly modified by the presence of the non-thermal electron component. In particular, the rarefactive solitary
and shock structures are found with smaller amplitude in comparison to the isothermal case. The transition from DIA solitary
to shock waves is also studied which is related to the contributions of the dispersive and dissipative terms. It is found
that the dust charge fluctuation is a source of dissipation, and is responsible for the formation of the dust ion-acoustic
shock waves. Furthermore, the dissipative effect becomes important and may prevail over that of dispersion as the population
of non-thermal electrons present decreases. The present investigation may be of relevance to electrostatic solitary structures
observed in many space dusty plasma, such as Saturn’s E-ring. 相似文献
9.
A theoretical investigation has been made of propagating electrostatic waves in a four-component adiabatic dusty plasma, whose
constituents are adiabatic electrons, adiabatic ions, adiabatic positively and as well as negatively charged warm dust. The
basic features of the solitary structures in such a four-component adiabatic dusty plasma are studied by the reductive perturbation
method. It is found that the presence of the positive dust component does not only significantly modify the basic properties
of the solitary waves, but also causes the existence of the positive solitary potential structures, which is an interesting
feature shown in an adiabatic dusty plasma with the dust of opposite polarity. It is also observed that the basic properties
(polarity, speed, amplitude and width) of the DA SWs are significantly modified by the effects of adiabaticity (γ>1) of electrons, ions, negatively as well as positively charged warm dust. The present investigation can be of relevance
to the electrostatic solitary structures observed in various dusty space plasma environments (viz. cometary tails, upper mesosphere,
Jupiter’s magnetosphere, etc.). 相似文献
10.
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
11.
Lunar swirls are albedo anomalies associated with strong crustal magnetic fields. Swirls exhibit distinctive spectral properties at both highland and mare locations that are plausibly explained by fine-grained dust sorting. The sorting may result from two processes that are fairly well established on the Moon, but have not been previously considered together. The first process is the vertical electrostatic lofting of charged fine dust. The second process is the development of electrostatic potentials at magnetic anomalies as solar wind protons penetrate more deeply into the magnetic field than electrons. The electrostatic potential can attract or repel charged fine-grained dust that has been lofted. Since the finest fraction of the lunar soil is bright and contributes significantly to the spectral properties of the lunar regolith, the horizontal accumulation or removal of fine dust can change a surface’s spectral properties. This mechanism can explain some of the spectral properties of swirls, accommodates their association with magnetic fields, and permits aspects of weathering by micrometeoroids and the solar wind. 相似文献
12.
In the present investigation, we have studied the linear and nonlinear propagation of electrostatic waves in a dense magnetoplasma with trapped electrons. Using the small amplitude approximation, formation of solitary structures has been studied both for fully and partially degenerate plasmas. The theoretical results obtained have been analyzed numerically for the parameters typically found in white dwarfs. The present work may be beneficial to understand the propagation of solitary structures with weak transverse perturbation with special reference to white dwarf asteroseismology. 相似文献
13.
Shantanu Kumar Biswal Santosh Kumar Agarwalla Munesh Chandra Adhikary 《Astrophysics and Space Science》2012,337(2):645-650
Some recent experimental observations have been shown that inclusion of electron collisions damping in inertial Alfvén wave
(IAW) dynamics may be important for laboratory as well as space plasmas. This paper presents the numerical simulation of model
equation governing the nonlinear dynamics of IAW in low-beta plasmas. When the nonlinearity arises due to the ponderomotive
force and Joule heating driven density perturbations, the model equation turns out to be a modified nonlinear Schr?dinger
equation (MNLS). The electron collisions are introduced only in the electron momentum equation. The damped localized structures
of IAW with sidebands are obtained. Also, the effect of collisional damping on power spectra of magnetic fluctuations with
different scaling laws has been studied. These turbulent structures may be responsible for particle acceleration in laboratory
and space plasmas. 相似文献
14.
Using the Sagdeev pseudo-potential technique, further investigation on the effect of nonextensive hot electrons on finite amplitude nonlinear low-frequency electrostatic waves in a magnetized two-component plasma have been reported in detail. The plasma model consists of cold ions fluid and nonextensively distributed electrons. The existence domain for the nonlinear structures have been established analytically and numerically. Apart from the compressive and rarefactive soliton solutions that have been reported earlier, the present investigation shows that double layer structures can be obtained for certain values of nonextensive electrons in the supersonic Mach number regime. The present results may provide an explanation for the observed nonlinear structures in the auroral region of the Earth’s magnetosphere. 相似文献
15.
A plasma simulation code is applied to interpret the instabilities in an expanding planetary nebula. The temperature of the
central star of a planetary nebula is assumed as above 50,000 K. Most of the atoms are ionized at this temperature. Since
ionization cannot be neglected for such a hot plasma, the electrostatic instability should be taken into account. In the one
dimensional electrostatic simulation, Maxwell and Vlasov equations are used and the fast Fourier transform is applied. The
calculated drift velocity in the simulation is found comparable with the expansion velocity of a planetary nebula. The linear
and non-linear behaviors of the simulated nebular plasma have been investigated in phase space; the simulation results agree
with the theory.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
16.
磁云因其独特的磁场结构经常是重大灾害性空间天气的驱动源.近来从磁云的边界层结构、环向通量、大尺度结构等方面关于磁云传播的动力学演化过程的研究取得了一些进展.在磁云边界存在一个由于磁场重联而形成的边界层结构.在磁云传播过程中,这种发生在边界处的磁场重联可能会把磁云的磁场剥蚀掉,进而引起其磁通量绳结构环向通量的减少以及不对称.在磁云内部,经常会观测到多个子通量绳结构.这些特性各异的子通量绳可以通过磁场重联而合并,进而引起磁云磁结构的改变.关于磁云大尺度磁场拓扑位形的演化机制,除了较早提出的交换重联外,目前的研究表明在行星际空间中,磁云边界处的重联过程也可以将磁云闭合或半开放的磁场线打开或断开.尽管在相关研究中已经取得了较大进展,但关于磁云传播的动力学演化过程还有许多问题尚不清楚.在行星际小尺度磁通量绳边界也发现了边界层结构,那么磁云是否会因剥蚀而成为小尺度通量绳?磁云内子通量绳结构在相互作用中会不会引起某些不稳定性而导致整个通量绳系统的崩溃?这些问题的解决还有待于进一步的理论、观测和数值模拟研究. 相似文献
17.
18.
K. Knott P.M.E. Decreau A. Korth A. Pedersen G.L. Wrenn 《Planetary and Space Science》1984,32(2):227-237
Electrostatic charging has given rise to problems on several geostationary spacecraft. This has led to a rigorous electrostatic cleanliness approach in the case of the scientific geostationary satellite GEOS in order to secure correct electric field and low energy plasma measurements. The present paper outlines the relevant charging mechanism, describes a new method for the determination of the equilibrium potential, and reports on actual potential measurements. The potentials observed are very closely related to the actual plasma conditions at the geostationary orbit. It is generally possible to use the potential measurements to characterize the particle population encountered by the spacecraft.Measurements carried out over a period of 4 years are presented by way of examples. A careful analysis shows that the chosen examples are representative and reflect the conditions observed on all other days of the mission. The results lead to the overall conclusion that the equilibrium potential of GEOS in sunlight is always moderately positive and only rarely exceeds + 10 V with respect to ambient space. At no instance in the sunlit portion of the orbit does the spacecraft assume a negative potential. We find that the observed moderate positive equilibrium potential generally is a function of cold plasma density. During the night and early morning part of the orbit we can, however, identify periods where the high energy particle population dictates the equilibrium potential. The electrostatic cleanliness design of GEOS avoids negative charging also under these conditions. In eclipse, a negative potential cannot be avoided but here the electrostatic cleanliness approach chosen for GEOS prevents any differential charging and avoids potentials of several thousand volts which have appeared on other satellites. The cost, in time and effort, of the precautions employed has clearly been justified. The specially developed techniques have since been used on other satellites and the lessons learned have also been applied successfully to operational spacecraft such as METEOSAT 2. 相似文献
19.
Distributions of plasma with excess numbers of superthermal electrons are common in space environments and double layer (DL)
is one of the very important electrostatic nonlinear wave structures ubiquitous in plasma systems. Based on the modified Zakharov
equations, the DLs are studied in the strong turbulent plasmas with Kappa distributed electrons. It appears that in the strong
turbulence regime, the presence of additional superthermal particles does not make qualitative changes on the DLs behavior,
but modify the thicknesses of the DLs. 相似文献
20.
Kiyotaka Tanikawa 《Celestial Mechanics and Dynamical Astronomy》2000,76(3):157-185
A numerical procedure to systematically find collision orbits in the planar three-body problem has been developed in the preceding
paper (Tanikawa et al., 1995). Using this procedure, a search for binary and triple collision orbits has been carried out
in the free-fall three-body problem. Some detailed structures of a part of the initial value space are discussed. Various
interesting orbits have been found. Examples are oscillatory orbits in which ejected particles change from ejection to ejection,
and orbits which are not isosceles initially but nearly isosceles after escape. Some results of isosceles problems (Simó and
Martínez, 1988) are extended to non-isosceles problems.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献