The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Q. Haque - One of the best experts on this subject based on the ideXlab platform.
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nonlinear dust drift alfven waves in rotating Planetary Magnetospheres
Physics of Plasmas, 2006Co-Authors: Q. Haque, H. SaleemAbstract:Linear and nonlinear electromagnetic waves are investigated in the dusty Magnetospheres of rotating planets. In the presence of heavy dust, the plasma may support very low frequency waves that can be affected by the plasma rotation. It is also shown that Alfven waves can couple with the electrostatic dust drift waves induced by the Planetary rotation. A comparison of the results with a previous work has also been made in the electrostatic limit. The electromagnetic vortex structures can be formed in rotating Planetary dusty plasmas in the nonlinear regime. An application of this theory to dusty plasmas of the Magnetospheres of Saturn and Jupiter is pointed out.
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Dust waves in rotating Planetary Magnetospheres
AIP Conference Proceedings, 2005Co-Authors: Q. Haque, H. SaleemAbstract:Low frequency electrostatic drift and acoustic waves are studied in rotating dusty plasmas. Linear dispersion relation is found. It is pointed out that rotation of the planet can introduce dust drift waves through Coriolis force in the Planetary Magnetospheres. This mode can couple with dust acoustic mode. Coriolis force effect may give rise to dipolar vortices in rotating dusty plasmas of Planetary Magnetospheres.
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rotation induced dust drift waves in Planetary Magnetospheres
Journal of Geophysical Research, 2004Co-Authors: Q. Haque, H. SaleemAbstract:[1] The linear and nonlinear electrostatic waves are studied in rotating dusty plasmas. It is pointed out that rotation can introduce dust drift waves through Coriolis force in the Planetary Magnetospheres. This wave can couple with dust acoustic mode. Owing to Doppler shift the frequencies can be very small. Coriolis force effect may give rise to dipolar vortices in rotating dusty plasmas of planetrary Magnetospheres. As an illustration, the results have been applied to Saturn's rings.
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Rotation‐induced dust drift waves in Planetary Magnetospheres
Journal of Geophysical Research, 2004Co-Authors: H. Saleem, Q. HaqueAbstract:[1] The linear and nonlinear electrostatic waves are studied in rotating dusty plasmas. It is pointed out that rotation can introduce dust drift waves through Coriolis force in the Planetary Magnetospheres. This wave can couple with dust acoustic mode. Owing to Doppler shift the frequencies can be very small. Coriolis force effect may give rise to dipolar vortices in rotating dusty plasmas of planetrary Magnetospheres. As an illustration, the results have been applied to Saturn's rings.
H. Saleem - One of the best experts on this subject based on the ideXlab platform.
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nonlinear dust drift alfven waves in rotating Planetary Magnetospheres
Physics of Plasmas, 2006Co-Authors: Q. Haque, H. SaleemAbstract:Linear and nonlinear electromagnetic waves are investigated in the dusty Magnetospheres of rotating planets. In the presence of heavy dust, the plasma may support very low frequency waves that can be affected by the plasma rotation. It is also shown that Alfven waves can couple with the electrostatic dust drift waves induced by the Planetary rotation. A comparison of the results with a previous work has also been made in the electrostatic limit. The electromagnetic vortex structures can be formed in rotating Planetary dusty plasmas in the nonlinear regime. An application of this theory to dusty plasmas of the Magnetospheres of Saturn and Jupiter is pointed out.
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Dust waves in rotating Planetary Magnetospheres
AIP Conference Proceedings, 2005Co-Authors: Q. Haque, H. SaleemAbstract:Low frequency electrostatic drift and acoustic waves are studied in rotating dusty plasmas. Linear dispersion relation is found. It is pointed out that rotation of the planet can introduce dust drift waves through Coriolis force in the Planetary Magnetospheres. This mode can couple with dust acoustic mode. Coriolis force effect may give rise to dipolar vortices in rotating dusty plasmas of Planetary Magnetospheres.
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rotation induced dust drift waves in Planetary Magnetospheres
Journal of Geophysical Research, 2004Co-Authors: Q. Haque, H. SaleemAbstract:[1] The linear and nonlinear electrostatic waves are studied in rotating dusty plasmas. It is pointed out that rotation can introduce dust drift waves through Coriolis force in the Planetary Magnetospheres. This wave can couple with dust acoustic mode. Owing to Doppler shift the frequencies can be very small. Coriolis force effect may give rise to dipolar vortices in rotating dusty plasmas of planetrary Magnetospheres. As an illustration, the results have been applied to Saturn's rings.
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Rotation‐induced dust drift waves in Planetary Magnetospheres
Journal of Geophysical Research, 2004Co-Authors: H. Saleem, Q. HaqueAbstract:[1] The linear and nonlinear electrostatic waves are studied in rotating dusty plasmas. It is pointed out that rotation can introduce dust drift waves through Coriolis force in the Planetary Magnetospheres. This wave can couple with dust acoustic mode. Owing to Doppler shift the frequencies can be very small. Coriolis force effect may give rise to dipolar vortices in rotating dusty plasmas of planetrary Magnetospheres. As an illustration, the results have been applied to Saturn's rings.
C T Russell - One of the best experts on this subject based on the ideXlab platform.
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new horizons in Planetary Magnetospheres
Advances in Space Research, 2006Co-Authors: C T RussellAbstract:Abstract The Magnetospheres of Mercury, the Earth and Jupiter provide an especially good comparison of the processes that control the behavior of Magnetospheres. The Mercurian magnetosphere is the smallest. Its field lines are anchored in the electrically conducting interior of Mercury and not in a conducting ionosphere. The Earth’s magnetosphere is over an order of magnitude larger than Mercury’s and its ionosphere is dynamically important. Also significant are that synchronous orbit occurs relatively far out in the magnetosphere and that the solar wind is responsible for the energization of processes therein. Jupiter’s magnetosphere is another two orders of magnitude larger. Its synchronous orbit, where gravity and centrifugal force balance, lies deep inside the magnetosphere, about 2% of the way to the magnetopause. Most importantly the jovian magnetosphere has a strong source of ions deep in the magnetosphere, but well outside of synchronous orbit, that are accelerated to high velocities. The energy of these accelerated ions and their centrifugal force are sufficient to drastically alter the behavior of the jovian magnetosphere so that it behaves much differently than the terrestrial magnetosphere. In this review, we examine what we know about each of these Magnetospheres in the areas in which their contrasts reveal the underlying controlling factors of magnetospheric behavior.
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the solar wind interaction with Planetary Magnetospheres
2005Co-Authors: C T Russell, X Blancocano, N Omidi, J Raeder, Y L WangAbstract:The solar wind interaction with Planetary Magnetospheres is a multifarious topic of which our understanding continues to grow as we obtain more detailed observations and more capable numerical codes. We attempt to explain how the system functions by examining the output of models of increasing sophistication. A gasdynamic numerical model produces a standing bow shock in front of a fixed impenetrable obstacle. The post-shock flow is heated and deflected but no plasma depletion layer is formed in the subsolar region contrary to observations. If magnetic forces are included, then a self-consistent obstacle size can be produced and plasma depletion extends all the way to the subsolar region. While a standing slow mode wave has been reported in the subsolar region, it appears that such a wave is not essential to the formation of a subsolar plasma depletion layer. Both the gasdynamic and magnetohydrodynamic models are self-similar. They do not change with the size of the obstacle. However, in the real solar wind interaction we expect that the relative scale size of ion motion and the radius of the obstacle will change the nature of the interactions. Hybrid simulations allow this multiscale coupling to be explored and shrinking the size of the obstacle relative to the gyroradius enhances the role of kinetic processes. Phenomena such as upstream ions, plasma sheet formation, and reconnection can be found in surprisingly tiny Magnetospheres. Finally, we contrast how the Magnetospheres of the Earth and Jupiter are powered. In the former case the solar wind interaction is very important and the latter case much less so.
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new horizons in Planetary Magnetospheres
cosp, 2004Co-Authors: C T RussellAbstract:The Magnetospheres of Mercury, the Earth and Jupiter provide an especially good comparison of the processes that control the behavior of Magnetospheres. The Mercurian magnetosphere is the smallest. Its field lines are anchored in the electrically conducting interior of Mercury and not in a conducting ionosphere. The Earths magnetosphere is over an order of magnitude larger than Mercurys and its ionosphere is dynamically important. Also significant are that synchronous orbit occurs relatively far out in the magnetosphere and that the solar wind is responsible for the energization of processes therein. Jupiters magnetosphere is another two orders of magnitude larger. Its synchronous orbit, where gravity and centrifugal force balance, lies deep inside the magnetosphere, about 2% of the way to the magnetopause. Most importantly the jovian magnetosphere has a strong source of ions deep in the magnetosphere, but well outside of synchronous orbit, that are accelerated to high velocities. The energy of these accelerated ions and their centrifugal force are sufficient to drastically alter the behavior of the jovian magnetosphere so that it behaves much differently than the terrestrial magnetosphere. In this review, we examine what we know about each of these Magnetospheres in the areas in which their contrasts reveal the underlying controlling factors of magnetospheric behavior. 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.
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multiscale coupling in Planetary Magnetospheres
Advances in Space Research, 2002Co-Authors: C T RussellAbstract:Abstract Processes in Planetary Magnetospheres occur on a variety of scales. On the largest scales are the plasma circulations induced in the magnetospheric plasma externally by the solar wind interaction or internally by processes such as massloading of the jovian magnetosphere by the moon Io. These large-scale processes are influenced by small-scale processes such as particle scattering by waves, gyro motion, and charge exchange. It is not always clear which of two coupled processes are in control. For example, many believe that the onset of reconnection requires a microscale instability but it is possible that external forcing leads to the magnetic configuration at which reconnection eventually occurs, and it is only the existence of the appropriate magnetic configuration over a sufficiently large region that is required to cause the macroscopic flows. This paper reviews such coupling in the Magnetospheres of the Earth and Jupiter.
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the dynamics of Planetary Magnetospheres
Planetary and Space Science, 2001Co-Authors: C T RussellAbstract:Abstract Mercury, Earth, Jupiter, Saturn, Uranus, Neptune, and the moon, Ganymede, have presently-active internal dynamos while Venus, Mars, at least two of the Galilean moons, the Earth's moon, comets and asteroids do not. These active dynamos produce magnetic fields that have sufficient strength to stand off the pressure of the exterior plasma environment. Because of changes in these exterior plasma environments these Magnetospheres are very dynamic. The jovian magnetosphere includes a strong time-varying energy source that adds to the dynamics of its magnetosphere and produces a quite different circulation pattern than that found at Earth and, presumably, Mercury. Not only intrinsic Planetary magnetic fields produce Magnetospheres but also unmagnetized planets. Venus, Mars and comets have induced Magnetospheres associated with the solar wind interaction with their atmospheres. Cometary Magnetospheres, parts of which can be remotely sensed, exhibit spectacular disruptions called tail disconnections. Even the atmosphereless bodies with weak magnetic fields can interact with the solar wind. Small magnetic anomalies on the moon and possibly asteroids cause weak deflections of the solar wind. The dynamics of these various Magnetospheres provide a rich spectrum of behavior which we review herein.
Danny Summers - One of the best experts on this subject based on the ideXlab platform.
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limit on stably trapped particle fluxes in Planetary Magnetospheres
Journal of Geophysical Research, 2009Co-Authors: Danny Summers, Rongxin Tang, R M ThorneAbstract:[1] We reexamine the Kennel-Petschek concept of self-limitation of stably trapped particle fluxes in a Planetary magnetosphere. In contrast to the original Kennel-Petschek formulation, we carry out a fully relativistic analysis. In addition, we replace the wave reflection criterion in the Kennel-Petschek theory by the condition that the limit on the stably trapped particle flux is attained in the steady state condition of marginal stability when electromagnetic waves generated at the magnetic equator acquire a specified gain over a given convective growth length. We derive relativistic formulae for the limiting electron integral and differential fluxes for a general Planetary radiation belt at a given L shell. The formulae depend explicitly on the spectral index and pitch angle index of the assumed particle distribution and on the ratio of the electron gyrofrequency to the electron plasma frequency. We compare the theoretical limits on the trapped flux with observed energetic electron fluxes at Earth, Jupiter, and Uranus.
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Ultra‐relativistic acceleration of electrons in Planetary Magnetospheres
Geophysical Research Letters, 2007Co-Authors: Danny Summers, Yoshiharu OmuraAbstract:[1] We present a new particle acceleration mechanism called ultra-relativistic acceleration (URA). URA comprises electron energization due to a special form of nonlinear phase trapping by a coherent whistler-mode wave for electrons with an initial Lorentz factor γ0 satisfying γ0 > ΩEQ/ω; ω is the wave frequency and ΩEQ is the electron cyclotron frequency at the equator of an assumed dipole magnetic field. Radiation belt electrons that encounter a combination of relativistic turning acceleration (RTA) followed by multiple URA interactions can undergo significant energy increase. Under ideal conditions, at Earth (L = 4) several-hundred-keV electrons can be energized to several MeV within a few seconds, while at Jupiter (L = 8), several-hundred-keV electrons can be energized by tens of MeV in a few tens of seconds. URA can play a prominent role in generating the several-MeV electrons observed in Earth's outer zone and the tens-of-MeV electrons observed in Jupiter's magnetosphere. More generally, we expect URA to be an effective electron energization mechanism in cosmic plasma environments that contain a magnetic mirror geometry and electromagnetic whistler-mode emissions.
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ultra relativistic acceleration of electrons in Planetary Magnetospheres
Geophysical Research Letters, 2007Co-Authors: Danny Summers, Yoshiharu OmuraAbstract:[1] We present a new particle acceleration mechanism called ultra-relativistic acceleration (URA). URA comprises electron energization due to a special form of nonlinear phase trapping by a coherent whistler-mode wave for electrons with an initial Lorentz factor γ0 satisfying γ0 > ΩEQ/ω; ω is the wave frequency and ΩEQ is the electron cyclotron frequency at the equator of an assumed dipole magnetic field. Radiation belt electrons that encounter a combination of relativistic turning acceleration (RTA) followed by multiple URA interactions can undergo significant energy increase. Under ideal conditions, at Earth (L = 4) several-hundred-keV electrons can be energized to several MeV within a few seconds, while at Jupiter (L = 8), several-hundred-keV electrons can be energized by tens of MeV in a few tens of seconds. URA can play a prominent role in generating the several-MeV electrons observed in Earth's outer zone and the tens-of-MeV electrons observed in Jupiter's magnetosphere. More generally, we expect URA to be an effective electron energization mechanism in cosmic plasma environments that contain a magnetic mirror geometry and electromagnetic whistler-mode emissions.
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pitch angle scattering rates in Planetary Magnetospheres
Journal of Plasma Physics, 2005Co-Authors: Danny Summers, R L Mace, Manfred A HellbergAbstract:The mechanism of gyroresonant scattering of charged particles by small-amplitude, broadband electromagnetic waves is examined. By means of quasi-linear theory, a simple expression for the resonant pitch-angle diffusion coefficient $D_{\alpha \alpha}$ is developed, which is valid for parallel-propagating, small-amplitude, (R-mode or L-mode) electromagnetic waves of general spectral density. We calculate the average diffusion coefficient with respect to the pitch-angle $\alpha$ , namely $\langle D_{\alpha\alpha}\rangle$ , which provides a practical estimate for particle scattering rates as a function of particle kinetic energy. The results for $\langle D_{\alpha\alpha}\rangle$ , corresponding to a Gaussian wave frequency spectrum, are used to estimate scattering rates for several types of wave–particle interactions in the terrestrial and Jovian Magnetospheres.
M Horanyi - One of the best experts on this subject based on the ideXlab platform.
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captured dust in Planetary Magnetospheres
Seventh workshop on the physics of dusty plasmas, 2008Co-Authors: J E Colwell, M Horanyi, E GrunAbstract:InterPlanetary and interstellar dust particles acquire a positive charge in the solar wind and can be strongly influenced by the Lorentz force as they pass through Planetary Magnetospheres. There, the charge on the particles changes rapidly when they pass through different plasma environments. This can lead to exchange of energy and angular momentum with the magnetosphere. Here we describe the discovery of captured grains in Jupiter’s magnetosphere by the Galileo dust detector and numerical simulations of the captured dust ring.
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global dynamics of charged dust particles in Planetary Magnetospheres
Physical Review Letters, 1999Co-Authors: J. E. Howard, M Horanyi, Glen R StewartAbstract:The dynamics of Planetary rings continues to presentsurprises and challenges to celestial mechanics. EarlierVoyager, Ulysses, and Galileo observations revealed com-plex dust rings around all four outer gaseous planets; nowthe impending visit of the Cassini orbiter promises toyield even more detailed information on Saturn’s magne-tosphere. Although much work has been done on the sta-bility of charged dust grains [1–6], these studies have beenlargely limited to negatively charged particles in prograde(corotating) equatorial orbits [1], or neglect perturbationstransverse to the equatorial plane [3]. Furthermore, thereare ample theoretical and experimental grounds [7] for thepresence of positively charged grains as well. In this Let-ter we carry out local and global stability analyses for bothpositively and negatively charged grains, in both progradeand retrograde orbits about an axisymmetric planet, an ex-cellent approximation for Saturn and a fair approximationfor Jupiter. We shall be primarily concerned with equa-torial orbits about Saturn; future publications will includeapplications to Jupiter’s rings, as well as the rather compli-cated dynamics of nonequatorial equilibria [8]. Our physi-cal model includes Keplerian gravity, corotating Planetarymagnetic field (taken to be an aligned centered dipole)with concomitant induced electric field. For single particledynamics over the short time scales envisioned here, it isreasonable to neglect radiation pressure, plasma drag, plan-etary oblateness, charge fluctuations, and collective effects[5]. The combined gravitational, magnetic, and electricforces are conveniently modeled by a two-dimensional ef-fective potential
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dust in Planetary Magnetospheres
Advances in Space Research, 1993Co-Authors: M HoranyiAbstract:Abstract Dust particles immersed in the magnetized plasma environment of Planetary Magnetospheres collect electrostatic charges. The expected charges are modest and only micron and smaller grains will be significantly perturbed by the resulting electrodynamic forces. These electrodynamic perturbations compete with other processes - radiation pressure, plasma and exospheric drag, etc. - and for micron (and smaller) grains result in energy and angular momentum exchange with the magnetospheric fields that dominate the orbital evolution of these small grains. The presence of dust also modifies the plasma environment. Sputtering, photo and secondary emissions, etc. are processes that couple the spatial and temporal evolution of the dust and the plasma. The study of this magnetospheric dusty plasma complex involves a large number of possible space experiments.