Magnetospheric Equilibrium Configurations and Slow Adiabatic Convection

Voigt, G. H.

doi:10.1007/978-94-009-4722-1_17

Cited by 58 publications

(47 citation statements)

References 54 publications

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“…Note, that this exact value of the destabilization factor is quite close to the original estimate C d ∼ 2/p made by Lembege and Pellat [1982] using a simple approximation of the flux tube volume V ∼ 2L z /B z where the integration over the flux tube was limited to a sheet thickness |z| < L z (the exact value of V was calculated for the first time by Hurricane et al [1996], though not in the context of the tearing stability analysis). It is also interesting that a similar result can be obtained for another equilibrium with y = −A 0 cos(pz/(2D)) exp(−ax) and the constant current sheet thickness L z ∼ D [Voigt, 1986], which does not even belong to the general class of the locally Harris sheets (2). As follows from Wolf et al [2006], for that model VB z /(2D) = 1.…”

Section: Stable Equilibriasupporting

confidence: 56%

Tearing stability of a multiscale magnetotail current sheet

Sitnov

Schindler

2010

Geophysical Research Letters

152

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The sufficient stability criterion of the collisionless ion tearing mode in the magnetotail current sheet, which was first obtained by Lembege and Pellat in 1982, is considered. For many conventional 2D current sheet equilibria, this criterion is satisfied within the WKB approximation, which is commonly interpreted as stability of those equilibria with respect to tearing. However, this is not necessarily the case for equilibria with more than two characteristic spatial scales. An example for substantial tearing destabilization of an equilibrium with accumulation of the magnetic flux at the tailward end of a thin current sheet is presented. Similar equilibria are reported in Geotail and THEMIS observations prior to onsets of magnetospheric substorms and dipolarization fronts associated with bursty bulk flows.

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Section: Stable Equilibriasupporting

confidence: 56%

Tearing stability of a multiscale magnetotail current sheet

Sitnov

Schindler

2010

Geophysical Research Letters

152

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“…Although recent observations have revealed very interesting fine structure in distribution functions observed in the central plasma sheet [Ashour-Abdalla et al, 1996], it is still reasonable in large-scale modeling to treat the central plasma sheet as isotropic [Stiles et al, 1978]. In such a situation, the theory of adiabatic drift implies that P V 5/3 is approximately constant along a drift path [Wolf, 1983], where P is the therma[ pressure of particles, and V is the volume of a unit magnetic flux tube. On the basis of the conventional assumption that plasma flows systematically earthward through the Earth's plasma sheet, one would expect the particle pressure P to vary with position in the plasma sheet in approximate proportion to V -5/3.…”

Section: Paper Number 1999ja900005mentioning

confidence: 99%

Theory of thin‐filament motion in Earth's magnetotail and its application to bursty bulk flows

Chen¹,

Wolf²

1999

J. Geophys. Res.

176

257

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Abstract. An MHD theory has been developed for the motion of a thin magnetic flux tube through a two-dimensional stationary medium that is in MHD equilibrium. The flux tube is represented as a one-dimensional filament. Simple properties of the computed time development of the filament are explored analytically, including linear intermediate and slow-mode waves, rotational discontinuities, and slow shocks. One numerical solution is presented in detail for a filament in the Earth's magnetotail that is initially underpopulated relative to its neighbors. The computed filament motion displays the strong earthward flow and reduced field line stretching that characterize bursty bulk flows, which are frequently observed in the plasma sheet of the Earth's magnetosphere. The solutions also display the propagation of MHD waves from the equatorial magnetosphere to the ionosphere, then partial reflection from the conducting ionosphere. The ionospheric end of the bursty-bulk-flow flux tube moves equatorward, but that motion is delayed relative to the earthward motion in the equatorial plane. The simulations illuminate the relationship between the interpretation of a bursty bulk flow (BBF) as an underpopulated flux tube and the fact that BBFs typically do not have significantly lower particle pressure than the neighboring plasma sheet. Though the simulated filament started out with lower particle pressure than its neighbors and thus started out as a "bubble" in the plasma sheet, its particle pressure rose to values comparable to, or sometimes greater than, its neighbors once its strong earthward motion developed.

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“…Auroral ovals and the configuration of the magnetopause can ben seen. VOIGT (1982) analyzed the magnetopause distance dependence on the IMF B.. The validity of the simulation is proved when the IMF, B, effect to the magnetopause distance is compared with the satellite data.…”

Section: Experiments and Resultsmentioning

confidence: 97%

“…In Fig. 3, obtained magnetopause stand-off distance, ro, as a function of the IMF B2, is shown together with the result by VOIGT (1982). For the laboratory simulation, the magnetopause stand-off distance is scaled to 10 RE when IMF is zero.…”

Section: Experiments and Resultsmentioning

confidence: 99%

“…These auroral oval dynamics dependence on the IMF was analyzed by PIKE et al (1974) and BURCH (1979). The satellite data analysis of the average magnetosphere and the bow shock dimension were made by FAIRFIELD (1971), BERCHEN andRUSSEL (1982), VOIGT (1982). The analysis of the cusp latitude dependence on the IMF were made by KAMIDE et al (1976), CARBARY andMENG (1986), andCANDIDI et a!.…”

Section: Introductionmentioning

confidence: 99%

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Laboratory Structure of the Magnetosphere Related to the Low Latitude Auroral Events.

Minami

1994

J. geomagn. geoelec

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We have made an interpretation of the cause of low latitude aurora event based on our laboratory result of the magnetosphere. The latitudinal change of auroral oval for the different solar wind parameters is investigated. To confirm the validity of the scaling of the laboratory simulation, an analysis of satellite data of the magnetopause stand-off distance dependence on the IMF B, is used. The scaling of the magnetic field proved the exact scaling of the experimental IMF value to the real value. The latitude of auroral oval can be obtained from photographs by illumination. The latitude of auroral oval in the night region dependence on the IMF B, is obtained. The result shows that the auroral oval latitude of almost 50 degrees in the night region is obtained for B, = -10 nT. The other investigation is made for the latitudinal dependence of the auroral oval on the solar wind dynamic pressure. The result shows that the latitude becomes to be low when the dynamic pressure is high. During the change of dynamic pressure, other parameters such as B, are fixed. The result also indicates a possibility of the cause of low latitude aurora for northward IMF. The observed events shows, however, the necessity of the creation of high energy auroral particles. For this meaning, the condition to cause the low latitude aurora events is pointed out showing the important role of the absolute value and the temporal change of the solar wind dynamic pressure.

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Magnetospheric Equilibrium Configurations and Slow Adiabatic Convection

Cited by 58 publications

References 54 publications

Tearing stability of a multiscale magnetotail current sheet

Tearing stability of a multiscale magnetotail current sheet

Theory of thin‐filament motion in Earth's magnetotail and its application to bursty bulk flows

Laboratory Structure of the Magnetosphere Related to the Low Latitude Auroral Events.

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