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1.
In the present paper, authors have investigated nonlinear interaction of inertial Alfvén wave with magnetosonic wave for low β-plasma (β?m e /m i ). Authors have developed the set of dimensionless equations in presence of ponderomotive force due to inertial Alfvén wave in the dynamics of magnetosonic wave. Stability analysis and numerical simulation have been carried out to study the effect of nonlinear coupling between waves which result in the formation of localized structures and density cavity, applicable to auroral region and solar corona. The result reveals that localized structure and density cavity becomes more complex and intense in nature in quasi steady state. From the obtained result, we found the density fluctuations ～0.1n 0, consistent with the FAST spacecraft observation. 相似文献
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S. K. El-Labany W. M. Moslem N. A. El-Bedwehy R. Sabry H. N. Abd?El-Razek 《Astrophysics and Space Science》2012,338(1):3-8
Rogue wave in a collisionless, unmagnetized electronegative plasma is investigated. For this purpose, the basic set of fluid
equations is reduced to the Korteweg-de Vries (KdV) equation. However, when the frequency of the carrier wave is much smaller
than the ion plasma frequency then the KdV equation is also used to study the nonlinear evolution of modulationally unstable
modified ion-acoustic wavepackets through the derivation of the nonlinear Schr?dinger (NLS) equation. In order to show that
the characteristics of the rogue wave is influenced by the plasma parameters, the relevant numerical analysis of the NLS equation
is presented. The relevance of our investigation to the Titan’s atmosphere is discussed. 相似文献
4.
Dispersion properties of kinetic Alfvén wave in quantum magnetoplasma are derived. The quantum contribution to the Landau damping of kinetic Alfvén wave is also derived by using linearized Vlasov equation which contains the Bohm quantum potential. Classical Landau damped kinetic Alfvén waves play an important role in turbulence of astrophysical plasmas. The quantum modification in Landau damping of kinetic Alfvén wave can also play a significant role in changing the scaling law of turbulent spectra as well as the formation of damped localized Alfvénic structures in dense astrophysical plasmas. 相似文献
5.
Fabrice Doveil Alessandro Macor Anass Aïssi 《Celestial Mechanics and Dynamical Astronomy》2008,102(1-3):255-272
The motion of charged particle in longitudinal waves is a paradigm for the transition to large scale chaos in Hamiltonian systems. Recently a test cold electron beam has been used to observe its non-self-consistent interaction with externally excited wave(s) in a specially designed Traveling Wave Tube (TWT). The velocity distribution function of the electron beam is recorded with a trochoidal energy analyzer at the output of the TWT. An arbitrary waveform generator is used to launch a prescribed spectrum of waves along the slow wave structure (a 4 m long helix) of the TWT. The resonant velocity domain associated to a single wave is observed, as well as the transition to large scale chaos when the resonant domains of two waves and their secondary resonances overlap. This transition exhibits a “devil’s staircase” behavior when increasing the excitation amplitude in agreement with numerical simulation. A new strategy for control of chaos by building barriers of transport which prevent electrons to escape from a given velocity region as well as its robustness are also successfully tested. Thus generic features of Hamiltonian chaos have been experimentally observed. 相似文献
6.
In the present paper, we investigate the localization of weak inertial Alfvén wave (IAW) in the presence of finite amplitude magnetosonic fluctuations in low β plasmas (β?m e /m i ). When IAW is perturbed by these fluctuations, localized structures of IAW magnetic field intensity are formed. We have developed a semi analytical model based on paraxial approximation to study this interaction. Numerical method has also been used to analyse the localized structures and magnetic fluctuation spectrum of IAW. From the obtained results, we find that the magnetic turbulent spectrum upto k x λ e ≈3 fits power law spectrum with an index consistent with the Kolmogorov $k_{x}^{ - 5/3}$ law, here λ e is the electron inertial length. Furthermore, at shorter wavelengths the spectrum steepens to about $k_{x}^{ - 3.8}$ . Energy transfer from larger lengthscales to smaller lengthscales through this mechanism may be responsible for the observed parallel electron heating in auroral region. Results obtained from the simulation are consistent with the observations recorded from various spacecrafts like FAST, Hawkeye and Hoes 2. 相似文献
7.
We suggest a two-step mechanism for the generation of the parallel electric field at the Alfvén wave. At the first step, the coupling with the compressional mode due to the magnetic field non-uniformity and finite plasma pressure provides the parallel magnetic field of Alfvén wave. At the second step, the compressional mode acquires the parallel electric field due to coupling with the electrostatic mode as required by the quasi-neutrality condition in kinetics. The parallel electric field acquired by the Alfvén mode is considerably larger than that due to the single-step coupling between the Alfvén and electrostatic modes in kinetics. 相似文献
8.
Amplitude modulation of quantum ion-acoustic waves (QIAWs) in a quantum electron-pair-ion plasma is studied. It is shown that
the quantum coupling parameter H (being the ratio of the plasmonic energy density to the Fermi energy) is ultimate responsible for the modulational stability
of QIAW packets, without which the wave becomes modulational unstable. New regimes for the modulational stability (MS) and
instability (MI) are obtained in terms of H and the positive to negative ion density ratio β. The growth rate of MI is obtained, the maximum value of which increases with β and decreases with H. The results could be important for understanding the origin of modulated QIAW packets in the environments of dense astrophysical
objects, laboratory negative ion plasmas as well as for the next generation laser solid density plasma experiments. 相似文献
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Based on the event observed by ISEE 3 near the Earth’s orbit at 01:21 UT on April 5, 1979, we investigate the diffusive shock acceleration of ions and the generation of Alfvén waves by accelerated particles near the quasi-parallel parts of interplanetary shock fronts within a quasi-linear approach. The theory is shown to give an excessively high level of Alfvén wave generation by accelerated particles at significant deflection angles of the interplanetary magnetic field from the normal to the shock front. At the Earth’s orbit, the Alfve´ n waves produced by accelerated ions are confined within the frequency range 5 × 10?2?0.5 Hz, and their spectral peak with a wave amplitude δB ≤ B corresponds to a frequency ν = (1?2)×10?2 Hz. The high-frequency part of the wave spectrum (ν ≥ 0.5 Hz) is subjected to damping on thermal protons. The calculated spectra of the accelerated ions and Alfvén waves generated by them reproduce the main features observed in experiments. 相似文献
11.
We re-formulate the 3+1 GRMHD equations for the Schwarzschild black hole in a Veselago medium. Linear perturbation in rotating
(non-magnetized and magnetized) plasma is introduced and their Fourier analysis is considered. We discuss wave properties
with the help of wave vector, refractive index and change in refractive index in the form of graphs. It is concluded that
some waves move away from the event horizon in this unusual medium. We conclude that for the rotating non-magnetized plasma,
our results confirm the presence of Veselago medium while the rotating magnetized plasma does not provide any evidence for
this medium. 相似文献
12.
D. I. Mendzhul O. V. Agapitov O. K. Cheremnykh 《Kinematics and Physics of Celestial Bodies》2013,29(3):107-119
The ray trajectories of waves in the very low frequency (VLF) range in the case of nonducted propagation in the earth’s inner magnetosphere are studied as functions of location of their source region, frequency, and initial angle between the vector of wave normal and intensity vector of external magnetic field. Simulation is performed on the basis of geometric ray tracing approach in multicomponent plasma. The parameters of the magnetospheric medium were calculated using a diffusion model of the concentration distribution of plasma components and the International Geomagnetic Reference Field (IGRF) model. It is shown that the magnetospheric wave reflection can occur if the lower hybrid resonance frequency is greater than its own wave frequency (ω LHF > ω), i.e., at the latitudes λ ≈ 50°. The simulation results confirm that the quasi-longitudinal approximation cannot be used to describe the magnetospheric whistler propagation. We present simulations of propagation of chorus-type wave magnetospheric emissions that were performed using realistic wave distributions over initial parameters. In particular, we present distributions of chorus waves over directions of wave vector as functions of geomagnetic latitude; these distributions are required to study the particle scattering and acceleration processes in the radiation belts. Our results well agree with CLUSTER satellite measurements. 相似文献
13.
De Yu Wang Guang Li Huang C. -G. Fälthammar P. A. Lindqvist L. Blomberg Li Ting Song 《Astrophysics and Space Science》1996,240(2):175-186
Nonlinear kinetic Alfvén waves where m
e
/m
i
, have been solved both with and without the Poisson equation correction. It is found that the ratio of the perpendicular electric field and magnetic field, and the ratio of parallel and perpendicular electric field increase with deepening of the depressive density soliton. The former ratio may be larger than the Alfvén velocity in the case of a large amplitude solitary kinetic Alfvén wave. The Poisson equation correction is important for the nonlinear kinetic Alfvén wave propagating along the magnetic field, which solves a puzzle of Sagdeev potential to approach infinity in the limit ofK
x
0. This correction causes the solitary KAW possessing an electrostatic character along the direction of wave moving frame. These results have been compared with the observations from the Freja satellite in the low aurora. 相似文献
14.
Previously developed solutions for pure toroidal mode Alfvén waves with finite ionosphere conductivities are modified to apply both inside and outside the plasmapause.Detailed diagrams are provided to illustrate the effect of realistic ionosphere conductances on the wave-forms. As well as graphs of wave-period, these include: (a) half-wave solutions showing the effect of dipole field distortion and consequent enhancement of ionosphere electric fields; (b) half-wave solutions with low damping that are symmetric and asymmetric about the equatorial plane; (c) highly-damped half-wave and quarter-wave solutions with wave admittance at the ionosphere nearly equal to the ionosphere conductance; (d) a quarter-wave solution with low damping that has a “near-node” of electric field at one ionosphere and an antinode of electric field at the other. 相似文献
15.
We have presented the localization of kinetic Alfvén wave (KAW) in intermediate β plasma (m e /m i ?β?1) by developing a model based on pump kinetic Alfvén wave and finite amplitude magnetosonic fluctuations. When KAW is perturbed by these background magnetosonic fluctuations, filamentary structures of KAW magnetic field are formed. First, a semi analytical model based on paraxial approximation has been developed to understand this evolution process. Localized structures and magnetic fluctuation spectrum of KAW has also been studied numerically for finite frequency of KAW. The calculated magnetic fluctuation spectrum follows two types of scalings. Above the proton gyroradius scale lengths (in inertial range), spectrum follows Kolmogorovian scaling. Below this scale dispersion starts and the spectrum steepens to about \(k_{x}^{-2.5}\) . The result shows the steepening of power spectra which can be responsible for particle acceleration in solar wind due to the energy transfer from larger to smaller lengthscales. Obtained magnetic turbulent spectra are consistent with observations of Cluster spacecraft in solar wind. 相似文献
16.
The 3+1 spacetime split is used in a preliminary investigation of waves propagating in a medium of isothermal plasma in the vicinity of event horizon of Reissner-Nordström planar analogue. The general relativistic magnetohydrodynamic equations for isothermal have been investigated there. The dispersion relations are obtained by using linear perturbation and Fourier analyze techniques for non-rotating and rotating, non-magnetized and magnetized environment. The wave number, phase velocity, group velocity etc. are shown to discuss the nature of the waves. 相似文献
17.
The instability of an inhomogeneous arbitrary- plasma occurring due to the transverse velocity shear, has been studied to analyse the effects of collisional thermal transfer. The dissipation of hydromagnetic waves in such a plasma has also been discussed. It has been found that the thermal forces modify the instability criteria in several limiting cases. Numerical solutions have also been obtained to investigate the effects of various physical parameters for a non-isothermal plasma with different adiabticity of two species, viz., electrons and ions. 相似文献
18.
A Korteweg-de Vries (KdV) equation with a linear Landau damping term describing weakly nonlinear and weakly dispersive ion-acoustic
waves in an electron-positron-ion plasma is derived. It is found that the Landau damping causes the solitary wave amplitude
to decay with time. It is also found that in absence of Landau damping, both linear wave phase velocity and solitary wave
amplitude decrease with the increase of positron density, whereas, both increase with the increase of positron temperature.
On the other hand, the Landau damping rate decreases with the increase of both positron density and temperature. 相似文献
19.
The processes of ion acceleration and Alfvén wave generation by accelerated particles at the Earth’s bow shock are studied within a quasi-linear approach. Steady-state ion and wave spectra are shown to be established in a time of 0.3–4 h, depending on the background level of Alfvénic turbulence in the solar wind. The Alfvén waves produced by accelerated ions are confined within the frequency range 10?2–1 Hz and their spectral peak with a wave amplitude βB ～ B comparable to the interplanetary magnetic field strength B corresponds to the frequency v = (2–3) × 10?2 Hz. The high-frequency part of the wave spectrum (v > 0.2 Hz) undergoes damping by thermal ions. The calculated spectra of the accelerated ions and the Alfvén waves generated by them reproduce the main features observed in experiments. 相似文献
20.
In the present paper, we have investigated nonlinear interaction of three dimensional (3D) inertial Alfvén wave and perpendicularly propagating magnetosonic wave for low β-plasma (β?m e /m i ). We have developed the set of dimensionless equations in the presence of ponderomotive nonlinearity due to 3D-inertial Alfvén wave in the dynamics of perpendicularly propagating magnetosonic wave. Stability analysis and numerical simulation has been carried out to study the effect of nonlinear coupling on the formation of localized structures and turbulent spectra, applicable to auroral region. The results reveal that the localized structures become more and more complex as the nonlinear interaction progresses. Further, we have studied the turbulent spectrum which follows spectral index (～k ?3.57) at smaller scales. Relevance of the obtained results has been shown with the observations received by various spacecrafts like FAST, Hawkeye and Heos 2. 相似文献