共查询到20条相似文献，搜索用时 31 毫秒
1.
The nonlinear interaction between finite amplitude electromagnetic ion-cyclotron waves and shear-Alfvén waves is considered. It is shown that this process is governed by three coupled equations. They are here used to study modulational instabilities. The relevance of our investigation to low-frequency electromagnetic fluctuations in space plasmas is pointed out. 相似文献
2.
A dispersion relation for left hand circularly polarized electromagnetic wave propagation in an anisotropic magnetoplasma in the presence of a very weak parallel electrostatic field has been derived with the help of linearized Vlasov and Maxwell equations. An expression of the growth rate has been derived in presence of parallel electric field for ion-cyclotron electromagnetic wave in an anisotropic media. The modification made in the growth rate by introducing parallel electric field and temperature anisotropy has been studied for fully ionized hydrogen plasma with the help of observations made on Jovian ionosphere and magnetosphere atL = 5.6 Rj. It is concluded that the growth (damping) of ion-cyclotron electromagnetic wave is possible when the wave vector is parallel (antiparallel) to the static electric field and effect is more pronounced at higher wave number. 相似文献
3.
The inductive electric field generated by a time-dependent symmetric ring current has been investigated. The symmetric ring current was modelled by a population of protons drifting in a magnetic dipole field. The interaction of these protons with ion-cyclotron waves was assumed to be the dominant energy loss process for the ring current protons, at least under certain conditions. The calculation, with spectral densities for the ion-cyclotron waves that are based on experimental data, showed that an azimuthal inductive electric field of as much as 0.25 mV/m can be produced by this mechanism. Furthermore there is evidence that if the spectral density of the waves is substantially larger than the one adopted here, the electric field might increase to the order of 1.0 mV/m or more. 相似文献
4.
R. Mecheri 《Solar physics》2013,282(1):133-146
Remote observations of coronal holes have strongly suggested the resonant interactions of ion-cyclotron waves with ions as a principal mechanism for plasma heating and acceleration of the fast solar wind. In order to study these waves, a WKB (Wentzel?CKramers?CBrillouin) linear perturbation analysis is used in the frame work of a collisionless multi-fluid model where we consider in addition to protons a second ion component made of alpha particles. We consider a non-uniform background plasma describing a funnel region in the open coronal holes and we use the ray tracing Hamiltonian-type equations to compute the ray path of the waves and the spatial variation of their properties. At low frequency (smaller than the proton cyclotron frequency), the results showed a distinct behavior of the two ion-cyclotron modes found in our calculations, namely the first one propagates anisotropically guided along the magnetic field lines while the second one propagates isotropically with no preferred direction. 相似文献
5.
This paper presents a set of solutions of coupled Einstein-Maxwell equations with matter for the Levi-Civita's metric which can be interpreted as electromagnetic mass models which are extensions of the electromagnetic mass models obtained previously. It may be pointed out that electromagnetic mass models are solutions of coupled Einstein-Maxwell equations with matter where all the characteristics of matter vanish when the charge vanishes. Existence of such solution tends to confirm Lorentz's conjecture that the mass of an electron may be of purely electromagnetic origin. 相似文献
6.
A scenario is proposed to explain the preferential heating of minor ions and differential-streaming velocity between minor ions and protons observed in the solar corona and in the solar wind. It is demonstrated by test-particle simulations that minor ions can be nearly fully picked up by intrinsic Alfvén-cyclotron waves observed in the solar wind based on the observed wave energy density. Both high-frequency ion-cyclotron waves and low-frequency Alfvén waves play crucial roles in the pickup process. A minor ion can first gain a high magnetic moment through the resonant wave–particle interaction with ion-cyclotron waves, and then this ion with a large magnetic moment can be trapped by magnetic mirror-like field structures in the presence of the low-frequency Alfvén waves. As a result, the ion is picked up by these Alfvén-cyclotron waves. However, minor ions can only be partially picked up in the corona because of the low wave energy density and low plasma β. During the pickup process, minor ions are stochastically heated and accelerated by Alfvén-cyclotron waves so that they are hotter and flow faster than protons. The compound effect of Alfvén waves and ion-cyclotron waves is important in the heating and acceleration of minor ions. The kinetic properties of minor ions from simulation results are generally consistent with in-situ and remote features observed in the solar wind and solar corona. 相似文献
7.
Juan Getino Ana B. González Alberto Escapa 《Celestial Mechanics and Dynamical Astronomy》2000,76(1):1-21
The study of the rotation of a non-rigid, non-symmetrical Earth with a heterogeneous and stratified liquid core was recently
accomplished by González and Getino (1997) through the Hamiltonian formalism. In this work that model is extended by including
the effect of the dissipation arising from the mantle–core interaction due to the viscous and electromagnetic coupling. A
canonical transformation to a new set of non-singular variables is performed, in order to avoid small divisors in the system
of equations. Numerical estimations of the effect of the dissipation are given in form of tables and graphics, and the significance
of this effect is discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
In this paper, the nonlinear dispersion relation for whistlers in the ionosphere has been derived and then the group travel time for an ion-cyclotron whistler from its source to an observer at the satellite has been theoretically calculated. It is seen that the nonlinear effect has some important contribution in the expression of group travel time. Our present analysis gives a more correct result than that obtained by Gurnett and others. From numerical estimations, it is found that the group travel time of whistler may be changed reasonably due to nonlinear interaction of the wave and the plasma of ionosphere. 相似文献
9.
The problem of the efficiency of the ion-synchrotron maser proposed by Hoshino and Arons is analyzed in a linear approximation.
A hot, relativistic, electron-positron plasma penetrated by a relativistic ion beam is considered. At the front of the magnetosonic
shock wave an electromagnetic wave is generated, which should be damped on positrons of the plasma. This should, in turn,
result in synchrotron emission from energetic positrons in the high-frequency range, far above the natural frequencies of
the plasma. It is shown that one must allow simultaneously for the conditions of resonance at a high harmonic of the ion-cyclotron
frequency and at the fundamental of the electron-cyclotron frequency. Natural transverse waves are generated in the process,
but within the framework of the linear theory there is no positron acceleration due to the kinetic energy of ions.
Translated from Astrofizika, Vol. 43, No. 3, pp. 389-396, July–September, 2000. 相似文献
10.
A complete dispersion relation for a whistler mode wave propagation in an anisotropic warm ion-electron magnetoplasma in the presence of parallel electric field using the dispersion relation for a circularly polarized wave has been derived. The dispersion relation includes the effect of anisotropy for the ion and electron velocity distribution functions. The growth rate of electron-ion cyclotron waves for different plasma parameters observed atL = 6.6R
E
has been computed and the results have been discussed in detail in the light of the observed features of VLF emissions and whistlers. The role of the combination of ion-cyclotron and whistler mode electromagnetic wave propagation along the magnetic field in an anisotropic Maxwellian weakly-ionized magnetoplasma has been studied. 相似文献
11.
R. Bharuthram P. K. Shukla M. Y. Yu V. N. Pavlenko 《Astrophysics and Space Science》1987,135(2):211-218
A set of coupled nonlinear differential equations which govern the dynamics of finite amplitude electromagnetic waves in the presence of an external current gradient in a magnetized electron-positron plasma has been derived. It is shown that the current gradient can make shear Alfvén-like waves unstable. A quasi-stationary solution of the mode-coupling equations is the well-localized dipole vortex. Application of our results to plasma transport in the pulsar magnetosphere is briefly discussed. 相似文献
12.
This paper presents a new class of well localized dipolar vortex solutions to the newly derived set of coupled nonlinear equations governing the dynamics of low-frequency electromagnetic waves in a strongly magnetized electron-positron plasma. 相似文献
13.
A set of fluid type equations is derived to describe the macroscopic behaviour of a plasma consisting of a mixture of matter and antimatter. The equations are written in a form which displays the full symmetry of the medium with respect to particle charge and mass, a symmetry absent in normal plasmas. This symmetry of the equations facilitates their manipulation and solution, and by way of illustration the equations are used to analyze the propagation of electromagnetic and acoustic waves through a matter-antimatter plasma. Some differences from the propagation of such waves in a normal plasma are noted. 相似文献
14.
With the German research satellite AZUR we observed repeatedly at low altitudes in the outer electron radiation belt, a double structure lasting from 6 to 8 days which is very distinct for energies >3-2 MeV. This phenomenon is discussed for a small and large geomagnetic storm by using simultaneous measurements of the geosynchronous ATS 5 satellite and magnetograms of polar stations. The double structure can probably be explained by a loss mechanism for relativistic electrons near the plasmapause due to a parasitic cyclotron interaction process with ion-cyclotron waves proposed by Thorne and Kennel. The example with the large geomagnetic storm also gives evidence for the injection and acceleration of high energy electrons in the outer radiation belt. 相似文献
15.
The interaction of ans-polarized plane electromagnetic wave incident from a dielectric (or vacuum) region on awarm moving magnetized plasma half-space is considered. The external magnetic field is assumed to be normal to the direction of the wave normal and the velocity of the moving medium. Using the first three moment equations, together with Maxwell's electromagnetic equations, we construct the constitutive relations in the rest frame of the moving medium. The constitutive relations are then transformed to the laboratory frame by invokingMinkowski's equations for the moving plasma medium, and the dispersion relation for the propagating ordinary mode in the moving medium is derived. Expressions are obtained for the phase and group velocities and the index of refraction for the ordinary mode, as also for power reflection and transmission coefficients. It is found that in contrast to the case of a cold magnetized plasma, the ordinary electromagnetic mode excited in the warm magnetoplasma medium getsmodified due to the presence of an external magnetic field. In addition, the various reflection and transmission characteristics for a warm magnetoplasma depend on the velocity of the moving plasma as well as on the strength of the applied magnetic field, as against the case for a cold moving magnetized plasma. Numerical results on the reflection coefficient are presented for several values of the parameters characterizing the electron-plasma temperature, the velocity of the moving medium and the strength of the applied magnetic field. 相似文献
16.
The dynamical properties of electromagnetic (EM) waves in ultra-relativistic electron-positron (EP) plasmas are analytically investigated on the basis of the nonlinear governing equations obtained from a kinetic way. It is shown that the EM wave envelope will collapse and be trapped into a localized region for the modulation interaction with low frequency density variation induced by ponderomotive force. The correlation between the localized strong wave field and the pulsar radio emission is discussed. 相似文献
17.
Starting from a set of general equations governing the dynamics of a magneto-fluid around a compact object on curved space
time, a fairly simple analytical solution for a test disc having only azimuthal component of velocity has been obtained. The
electromagnetic field associated has a modified dipole configuration which admits a reasonable pressure profile for the case
of fully relativistic treatment of Keplerian type of velocity distribution 相似文献
18.
Vladimir Ivanchenko Paolo Dondero Valentina Fioretti Anton Ivantchenko Fan Lei Simone Lotti Alfonso Mantero Teresa Mineo 《Experimental Astronomy》2017,44(3):437-450
Monte Carlo simulation of space radiation effects induced by protons is important for design of space missions. Geant4 is a well established toolkit for Monte Carlo simulation focused on high energy physics applications. In this work, a set of new validation results versus data for Geant4 electromagnetic and hadronic interaction of protons is presented and discussed. Optimal configuration of Geant4 physics for space applications is proposed. 相似文献
19.
Nonlinear interaction of finite-amplitude Alfvén waves with non-resonant finite-frequency electrostatic and stationary electromagnetic perturbations is considered. This interaction is governed by a pair of coupled equations consisting of nonlinear Schrödinger equation for the Alfvén wave envelope and an equation for the plasma slow response that is driven by the ponderomotive force of the Alfvén wave packets. The modulational instability of a constant amplitude Alfvén pump is investigated and some new results for the growth rate of the instability are presented. It is found that a possible stationary state of the modulated Alfvén wave packets could lead to localized structures. The relevance of our investigation to the solar atmosphere is discussed. 相似文献
20.
On the basis of bi-Maxwellian velocity distribution functions it has been recently shown that the combined effect of heavy ion thermal anisotropy and drift velocity can trigger ion-cyclotron instabilities beyond the corresponding heavy ion-cyclotron frequency. (Proton-cyclotron instability induced by the thermal anisotrophy of minor ions. J. Geophys. Res. 107 (2002) 1494; Ion-cyclotron instability due to the thermal anisotrophy of drifting ion species. J. Geophys. Res. 108 (2003) 1050.) Here we show that the cascade-type mechanism proposed by Gomberoff and Valdivia (2002, 2003) can take place in the region where main heating of the fast solar wind seems to occur (i.e. within 10 solar radii). We also compare some of the results obtained by using the semi-cold approximation with the exact kinetic dispersion relation. 相似文献