共查询到20条相似文献，搜索用时 24 毫秒
1.
In high-speed solar wind, propagating Alfvén waves can be transferred into fast magnetosonic waves. When both the magnetic field strength and Alfvén wave velocity approach zero, fast magnetosonic waves will be transferred into ion-acoustic waves. As the phase velocity of ion-acoustic waves is slightly greater than the thermal velocity of protons, the turbulence energy of ion-acoustic waves can largely be absorbed by protons and can cause the mean temperature of protons to be greater than that of electrons by stochastic turbulence heating of ion-acoustic waves for protons. 相似文献
2.
A model for ion-acoustic waves in the solar atmosphere is presented. In the limit of strongly magnetized plasma this model leads to the Zakharov-Kuznetsov equation which possesses a flat solitary wave solution. An initial-value problem for this equation is solved numerically to show a transition of the flat solitary waves into spherical solitary waves. The paper suggests further developments of an ion-acoustic wave theory that may improve our knowledge of ion-acoustic waves and lead to the possibility of their being detected in the solar atmosphere. 相似文献
3.
It is shown that a fast ion-acoustic wave can decay into another ion-acoustic wave and a whistler wave. The results are applied to interpret wave spectra measurements in the foreshock region of the Earth's bowshock. 相似文献
4.
Based on model calculations, we show that ion-acoustic oscillations can be excited by heat fluxes in a plasma. We discuss the probable effect of ion-acoustic oscillations on the formation of temperature gradients at critical heat fluxes. The local critical heat flux in the transition region of the solar atmosphere is close to the well-known experimental heat flux from the corona into the chromosphere. 相似文献
5.
Gui-Ping Wu Guang-Li Huang Yu-Hua TangDepartment of Physics Southeast University Nanjing Purple Mountain Observatory Chinese Academy of Sciences Nanjing Department of Astronomy Nanjing University Nanjing 《中国天文和天体物理学报》2005,5(1):99-109
Through solving the single electron equation of motion and the Fokker-Planck equation including the terms of electric field strength and ion-acoustic turbulence, we study the influence of the ion-acoustic wave on the electron acceleration in turbulent reconnecting current sheets. It is shown that the ion-acoustic turbulence which causes plasma heating rather than particle acceleration should be considered. With typical parameter values, the acceleration time scale is around the order of 10^-6 s, the accelerated electrons may have approximately a power-law distribution in the energy range 20 ～100 keV and the spectral index is about 3～10, which is basically consistent with the observed hard X-ray spectra in solar flares. 相似文献
6.
S. A. El-Tantawy N. A. El-Bedwehy S. Khan S. Ali W. M. Moslem 《Astrophysics and Space Science》2012,342(2):425-432
Arbitrary amplitude ion-acoustic solitary waves propagating in a magnetized plasma composed of positive ions, superthermal electrons and positrons are investigated. For this purpose, the ions are represented by the hydrodynamical fluid equations while the non-Maxwellian electrons and positrons densities are assumed to follow kappa (κ) distribution. The basic equations are reduced to a pseudoenergy-balance equation. Existence conditions for large amplitude solitary waves are presented. The analytical and numerical analysis of the latter show that the ion-acoustic solitary wave can propagate only in the subsonic region in our plasma system and it is significantly influenced by the plasma parameters. The present analysis could be helpful for understanding the nonlinear ion-acoustic solitary waves propagating in interstellar medium and pulsar wind, which contain an excess of superthermal particles. 相似文献
7.
The KdV equation is derived for weakly nonlinear ion-acoustic waves in an unmagnetized warm dusty plasma with electron inertia.
It has been shown that the inclusion of electron inertia and pressure variation of the species not only significantly modifies
the basic features (width and amplitude) of dust ion-acoustic solitions, but also introduces a new parametric regime for the
existence of positive and negative solitons. 相似文献
8.
Yasunori Nejoh 《Astrophysics and Space Science》1996,235(2):245-253
The stationary ion-acoustic double layer is investigated in a plasma with an electron beam. The condition of the existence sensitively depends on the parameters such as the electron beam temperature, the ion temperature, the beam density and the effect of the trapped electrons. The properties of the double layer are also depicted. It turns out that the electron beam velocity is relatively small. This investigation predicts new findings of the ion-acoustic double layers in a plasma with an electron beam. 相似文献
9.
H. Alinejad 《Astrophysics and Space Science》2011,331(2):611-618
The effects of dust charge fluctuations and deviations from isothermality of electrons are incorporated in the study of nonlinear
dust ion-acoustic waves. Deviations from isothermality of electrons are included in this model as a result of nonlinear resonant
interaction of the electrostatic wave potential with electrons during its evolution. The basic properties of stationary structures
are studied by employing the reductive perturbation method, and conditions for the formation of small but finite amplitude
dust ion-acoustic solitary waves in the space dusty plasma situations are clearly explained. It is shown that a more depletion
of the background free electrons owing to the attachment of these electrons to the surface of the dust grains during the charging
process can lead to the formation of solitary waves with smaller amplitude. Furthermore, effects of the dust charge fluctuation
and deviations from isothermality of electrons show a non-uniform behavior for the amplitude of solitary waves in transition
from the Boltzmann electron distribution to a trapped electron one. It is also found that the dust charge fluctuation caused
by trapped as well as free electrons is a source of dissipation, and is responsible for the formation of the dust ion-acoustic
shock waves. 相似文献
10.
C.-V. Meister 《Astronomische Nachrichten》1995,316(5):295-310
A Langevin equation for charged particles in a plasma with electrostatic turbulence is developed from first principles and in consistency with the kinetic theory in polarization approximation. For the case of ion-acoustic and electrostatic lower-hybrid-drift turbulence approximate expressions for the space-time spectral density of the wave energy are given and estimates of the intensities of the stochastic wave forces are made. The application is done for the plasmas of the earth's magnetosphere, the solar wind and solar flares. It seems, that ion-acoustic and electrostatic lower-hybrid-drift waves can contribute to electron chaotization in different regions of the space plasma. 相似文献
11.
12.
The possibility is investigated that the plasma turbulence used in many recent models of the primary energy release and acceleration in solar flares should be detectable by radiation near the fundamental and second harmonic of the plasma frequency. Formulae are derived for fundamental emission due to the combination of ion-acoustic and Langmuir plasma turbulence and for second harmonic emission due to the combination of two Langmuir waves. These results are applied to recent primary energy release and acceleration models which shows that either such radiation should be detectable and possibly distinguishable with suitable microwave interferometers or that its absence places fairly stringent constraints on the possible level of Langmuir or Langmuir and ion-acoustic waves in these models.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
13.
The Ulysses Unified Radio and Plasma Wave Experiment (URAP) has observed Langmuir, ion-acoustic and associated solar type
III radio emissions in the interplanetary medium. Bursts of 50–300 Hz (in the spacecraft frame) electric field
signals, corresponding to long-wavelength ion-acoustic waves are often observed coincident in time with the most intense Langmuir
wave spikes, providing evidence for the electrostatic decay instability. Langmuir waves often occur as envelope solitons,
suggesting that strong turbulence processes, such as modulational instability and soliton formation, often coexist with weak
turbulence processes, such as electrostatic decay, in a few type III burst source regions. 相似文献
14.
A weakly nonlinear analysis is carried out to derive a Korteweg–de Vries-Burgers-like equation for small, but finite amplitude,
ion-acoustic waves in a dissipative plasma consisting of weakly relativistic ions, thermal positrons and nonextensive electrons.
The travelling wave solution has been acquired by employing the tangent hyperbolic method. Our results show that in a such
plasma, ion-acoustic shock waves, the strength and steepness of which are significantly modified by relativistic, nonextensive
and dissipative effects, may exist. Interestingly, we found that because of ion kinematic viscosity, an initial solitonic
profile develops into a shock wave. This later evolves towards a monotonic profile (dissipation-dominant case) as the electrons
deviate from their Maxwellian equilibrium. Our investigation may help to understand the dissipative structures that may occur
in high-energy astrophysical plasmas. 相似文献
15.
H. Alinejad 《Astrophysics and Space Science》2012,337(2):637-643
A theoretical investigation is carried out for understanding the basic features of oblique propagation of linear and nonlinear
ion-acoustic waves subjected to an external magnetic field in an electron-positron-ion plasma which consists of a cold magnetized
ion fluid, Boltzmann distributed positron, and electrons obeying a trapped distribution. In the linear regime, two dispersion
curves are obtained. It is shown that the positron concentration causes the both modes to propagate with smaller phase velocities.
Then, owing to the presence of resonant electrons, the modified Korteweg-de Vries equation describing the nonlinear dynamics
of small but finite amplitude ion-acoustic waves is derived. It is found that the effects of external magnetic field (obliqueness),
trapped electrons, positron concentration and temperature ratio significantly modify the basic features of solitary waves. 相似文献
16.
Astrophysics and Space Science - Electrostatic (ES) waves generated in space plasmas, e.g., Langmuir and ion-acoustic waves, are subject to multiple applications, such as plasma diagnosis,... 相似文献
17.
A parametric survey on the propagation characteristics of the dust ion-acoustic (DIA) shock waves showing the effect of nonextesivity with nonextensive electrons in a dissipative dusty plasma system has been carried out using the reductive perturbation technique. We have considered continuity and momentum equations for inertial ions, q-distributed nonextensive electrons, and stationary charged dust grains, to derive the Burgers equation. It has been found that the basic features of DIA shock waves are significantly modified by the effects of electron nonextensivity and ion kinematic viscosity. Depending on the degree of nonextensivity of electrons, the dust ion-acoustic shock structures exhibit compression and rarefaction. The implications of our results would be useful to understand some astrophysical and cosmological scenarios like stellar polytropes, hadronic matter and quark-gluon plasma, protoneutron stars, dark-matter halos, etc., where effects of nonextensivity can play the significant roles. 相似文献
18.
The propagation of ion-acoustic waves by the augmentation of Kadomtsev-Petviashvili equation are studied in a plasma in relation to that existing in the interplanetary space. We precisely pointed out the causes of occuring the double layers as well as collapsing of the solitary waves in the plasma dynamics. 相似文献
19.
20.
N. D'Angelo 《Solar physics》1969,7(2):321-328
The suggestion is advanced that heating of the solar corona results from Landau damping of ion-acoustic waves generated in the motion of photospheric granules. Laboratory experiments relevant to the question of corona heating are discussed, together with the available observational information on the extent of energy deposition in the corona.Of the European Space Research Organization (ESRO). 相似文献