Comparison of self-consistent simulations with observed magnetic field and ion plasma parameters in the ring current during the 10 August 2000 magnetic storm

The evidence in favour of a corpuscular theory of magnetic storms is briefly reviewed and reasons given for believing that the stream must be neutral but ionized and carry no appreciable current. It is shown that under suitable conditions the stream is able to pass freely through a solar magnetic field; the stream may also be able to carry away with it a part of this field. However, because of geometrical broadening of the stream during its passage from the sun to the earth, the magnetic field imprisoned in the gas may be wellnigh unobservable near the earth.The nature, composition and dimensions of the stream near the earth are discussed and it is concluded that on arrival the stream will present very nearly a plane surface to the earth if undistorted by the magnetic field.Because of its large dimensions, the stream will behave as if it were perfectly conducting. During its advance in the earth's magnetic field the currents induced in the stream will therefore be practically confined to the surface. The action of the magnetic field on this current is to retard the surface of the stream which being highly distortible will become hollowed out. Since the stream surface is impervious to the interpenetration of the magnetic tubes of force, these will be compressed in the hollow space. The intensity of the magnetic field is thereby increased and this increase is identified with the beginning of the first phase of a magnetic storm. This increase will be sudden, as observed, owing to the rapid approach of the stream to the earth.The distortion of the stream surface is discussed and it is pointed out that two horns will develop on the surface, one north and the other south of the geomagnetic equator. Matter pouring through these two horns will find its way to the polar regions.The main phase of a magnetic storm seems most simply explained as due to a westward ring-current flowing round the earth in its equatorial plane. Under suitable conditions such a ring-current would be stable if once set up. The mode of formation of the ring is, however, largely conjectural. The possibility that the main phase may be of atmospheric origin is also briefly considered. It is shown that matter passing through the two horns to the polar regions could supply the energy necessary for the setting up of the field during the main phase. The magnetic evidence in favour of such a hypothesis, however, seems wanting.

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LABORATORY SIMULATION OF THE SOLAR WIND MAGNETOSPHERE INTERACTION

Canadian Journal of Physics ◽

10.1139/p63-178 ◽

1963 ◽

Vol 41 (11) ◽

pp. 1747-1752 ◽

Cited By ~ 13

Author(s):

F. J. F. Osborne ◽

I. P. Shkarofsky ◽

J. V. Gore

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Magnetic Storm ◽

Ring Current ◽

Laboratory Simulation ◽

Field Interaction ◽

Trapping Region ◽

Moving Plasma ◽

Geophysical Measurements ◽

Current Mechanism

A controlled plasma–magnetic field interaction has been achieved, the conditions of which are such as to fulfill generally the scaling considerations of some aspects of geophysical phenomena, in particular the initial commencement of a magnetic storm. The preliminary measurements indicate the sweeping action on a magnetic field by a moving plasma; the formation of a magnetic cavity; the motion of the "dip pole" under perturbed conditions; the stand-off of plasma; a quasi Van Allen belt whose drift westward can be suggested as a ring current mechanism; and a polar trapping region. The correlations between the laboratory observations, geophysical measurements, and related theories, where possible, show no serious discrepancies as yet.

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Dynamics of the electrojet during intense magnetic disturbances

10.5194/angeo-2018-31 ◽

2018 ◽

Author(s):

Liudmila I. Gromova ◽

Matthias Förster ◽

Iakov I. Feldstein ◽

Patricia Ritter

Keyword(s):

Magnetic Field ◽

Magnetic Storm ◽

Current Density ◽

Ring Current ◽

Geomagnetic Storms ◽

Flow Direction ◽

Main Phase ◽

Local Times ◽

Temporal Behaviour ◽

The Imf

Abstract. Hall current variations in different time sectors during six magnetic storms of the summer seasons in 2003 and 2005 are examined in detail: three storms in the day-night meridional sector and three storms in the dawn-dusk sector. We investigate the sequence of the phenomena, their structure, positions and the density of the polar (PE) and the auroral (AE) Hall electrojets using scalar magnetic field measurements obtained from the CHAMP satellite in accordance with the study of Ritter et al. (2004a). Particular attention is devoted to the spatial-temporal behaviour of the PE at ionospheric altitudes during daytime hours both under geomagnetically quiet and under magnetic storm conditions. We analyze the correlations of the PE and AE with various activity indices like SYM/H and ASYM/H, that stand for large-scale current systems in the magnetosphere, AL for ionospheric currents, and the IndN coupling function for the state of the solar wind. We obtain regression relations of the magnetic latitude MLat and the electrojet current density I with those indices and with the interplanetary By and Bz magnetic field components. For the geomagnetic storms during summer seasons investigated here, we obtain the following typical characteristics for the electrojets' dynamics: 1. The PE appears at magnetic latitudes (MLat) and local times (MLT) of the cusp position. 2. This occurs in the day-time sector at MLat ∼ 73°–80° with a westward or an eastward direction, depending on the orientation of the IMF By component. Changes of current flow direction in the PE can occur repeatedly during the storm, but only due to changes of the IMF By orientation. 3. The current density in the PE increases with the intensity of the IMF By component from I ∼ 0.4 A/m for By ∼ 0 nT up to I ∼ 1.0 A/m for By ∼ 23 nT. 4. The MLat position of the PE does not depend on the orientation and the strength of the IMF By component. It depends, however, on the strength of the IMF Bz component. 5. The PE is situated at MLat ∼ 73° on the dayside during geomagnetically quiet periods and the recovery phase of a magnetic storm, and it shifts equatorward during intense substorms and the main phase of a storm. 6. There is no connection between MLat and the current density I in the PE with the magnetospheric ring current DR (index SYM/H). 7. There is a correlation between the current density I in the PE and the partial ring current in the magnetosphere (PRC, index ASYM/H), but practically no correlation of this index with MLat of the PE. 8. Substorms that occur before and during the beginning of a storm main phase are accompanied in the daytime by the appearance of an eastward electrojet (EE) at MLat ∼ 64° and then also by a westward electrojet (WE). In the nighttime sector the WE appears at MLat ∼ 64°. 9. During the development of the main storm phase, the daytime EE and the nighttime WE shift toward subauroral latitudes of MLat ∼ 56° and intensify up to I ∼ 1.5 A/m. Both electrojets persist during the main phase of the storm. The WE is then located about 6° closer to the pole than the EE during evening hours and about 2°–3° during daytime hours.

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On the effect of baryon loading in magnetized counterstreaming plasmas. II. Particle-in-cell simulations

Journal of Plasma Physics ◽

10.1017/s0022377808007216 ◽

2008 ◽

Vol 74 (6) ◽

pp. 815-826 ◽

Cited By ~ 2

Author(s):

R. C. TAUTZ ◽

J.-I. SAKAI

Keyword(s):

Magnetic Field ◽

Particle In Cell ◽

Particle Species ◽

Ion Plasma ◽

Electron Positron ◽

Background Magnetic Field ◽

Self Consistent ◽

Homogeneous Background

AbstractAssuming a non-relativistic three species electron–positron–ion plasma, the counterstreaming instability is investigated for waves propagating parallel and perpendicular to a homogeneous background magnetic field. To support previous analytical investigations (Tautz and Sakai 2007), the instability is investigated by means of self-consistent particle-in-cell simulations. It is shown that the presence of a third particle species is responsible for a variety of new features that cannot be seen either from an electron–ion plasma or for an electron–positron plasma.

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