Measurement of auroral Birkeland currents and energetic particle fluxes

Cloutier, P. A.; Sandel, B. R.; Anderson, H. R.; Pazich, P. M.; Spiger, R. J.

doi:10.1029/ja078i004p00640

Cited by 47 publications

(10 citation statements)

References 8 publications

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“…If the electron thermal energy is assumed to be 100 eV, the energy of accelerated electrons reaches to 1 ∼ 10 keV. This is comparable with that of observed auroral energetic electrons [15][16][17][18].…”

Section: Simulation Resultssupporting

confidence: 65%

Improved Open Boundary Model for Plasma Particle Simulations

Hasegawa

Sato

2010

Plasma and Fusion Research

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An open system one-dimensional electrostatic particle code that adopts the new constant current generator model has been developed. Using this new model, we have been able to study various phenomena at large electron drift velocities, where the original model is not applicable. In this new model, the contribution of the ion flux, which is not considered in the original model, is added into the electric current. By examining the code, we find that the result in a case where the electron drift velocity is smaller than the electron thermal velocity is similar to that of a previous study, which showed double layer creation as a result of ion-acoustic instability. We also present the results of simulations of an electron drift velocity comparable to or larger than the electron thermal velocity.

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Section: Simulation Resultssupporting

confidence: 65%

Improved Open Boundary Model for Plasma Particle Simulations

Hasegawa

Sato

2010

Plasma and Fusion Research

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“…They deduced a pair of oppositely directed field-aligned current sheets, the poleward sheet with an upward current being coincident with the visible arce and the equatorward sheet with a downward current being displaced to the south of the visible arc. Cloutier et al (1973) made another rocket observation of field-aligned currents in association with two visible auroral arcs and presented two models of field-aligned currents that could explain the observed features.…”

Section: 17mentioning

confidence: 99%

Identifications of the polar cap boundary and the auroral belt in the high-altitude magnetosphere: A model for field-aligned currents

Sugiura¹

1975

J. Geophys. Res.

116

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Using the OGO-5 GSFC-fluxgate magnetometer data, the polar cap boundary is identified in the high-altitude magnetosphere by a sudden transition from a dipolar field to' a more tail-like configuration. It is inferred that there exists a field-aligned current layer at the polar cap boundary. In the nightside magnetosphere the polar cap boundary is identified as the high-latitude boundary of the plasma sheet. The fieldaligned current flows downward to the ionosphere on the morning side of the magnetosphere and upward from the ionosphere on the afternoon side.Thus in the high-latitude boundary layer of the plasma sheet in the tail, the current is toward the earth in the post-midnight region and away from the earth before midnight. The basic pattern of the magnetic field variations observed during the satellite's traversal of the auroral belt is presented. This pattern shows the existence of a field-aligned current layer on the equator side of the polar cap boundary. Currents flow in the opposite directions in the two field-aligned current layers. The current directions in these layers as observed by OGO-5 in the highaltitude magnetosphere are the same as those observed at low altitudes by the polar orbiting TRIAD satellite (Armstrong and Zmuda, 1973). The magnetic field in the region where the lower-latitude field-aligned current layer is situated is essentially meridional. Thus the equatorial current closure of this current system must be via the equatorial current sheet. The two field-aligned current systems, one at the polar cap boundary and the other on the low-latitude side of the auroral belt, are coupled through the Pedersen current in the ionosphere. The coupling is weak during magnetically quiet periods and becomes strong at disturbed times.Even during intense disturbances the basic pattern of the field variations in the critical regions of the auroral belt and the polar cap boundary is the same as at quiet times. Intensifications of the field-aligned currents and the appearances of multiple pairs of field-aligned current layers characterize the disturbed conditions of these regions.

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“…The Rice University group has published a number of papers which present in situ useful data capable of testing any theoretical model of quiet auroral arcs [Vondrak et al, 1971;Park and Cloutier, 1971;Cloutier et al, 1973' Anderson andPazich and Anderson, 1975;Spiger and Anderson, 1975;Casserly and Cloutier, 1975;Sesiano and Cloutier, 1976 downward currents do not include auroral (-• 5 keV) electrons, upward currents consist of ambient electrons (<500 eV)and auroral electrons, though the latter contribution is often minor, say, 20%; (4) associated electrojets can either be westward or eastward; (5) arcs usually move equatorward with speeds of the order of 100 m s-X; (6) the field-aligned current intensity is of the order of 10 tzA/m 2, and the electrojet current is of the order of 10 a A; and (7) the arc width is typically 20 km, and the spacing, when it is multiple, is also about the same as the arc width. The underlying physics of the present feedback instability model is described elsewhere [Ogawa and Sato, 1971;Sato and Holzer, 1973].…”

Section: Introductionmentioning

confidence: 99%

A theory of quiet auroral arcs

Sato¹

1978

J. Geophys. Res.

212

222

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Being fed by the large‐scale magnetospheric convection, the coupled ionosphere‐magnetosphere system is subject to a feedback instability for a conjugate perturbation elongating in the east‐west direction, having a width of several tens of kilometers at the ionospheric level, standing along the magnetic field line. The growth time is as short as several minutes even when no hot electrons are involved in the field‐aligned current. Nonlinear development of the feedback instability is numerically investigated, taking hot electrons into account. The following conclusions are obtained. (1) An auroral arc can develop within a few tens of seconds once hot electrons take part. (2) The induced potential associated with the arc can reach several hundred volts. This predicts that the upward field‐aligned current may be provided by electrons with energies of the order of several hundred electron volts, provided anomalous resistivity or double layers develop. (3) The electron density enhancement is directly connected with the upward field‐aligned current and hence the auroral arc. (4) The downward current is localized equatorward of the upward current, when the background electric field is westward. (5) The electrojet current can grow to a few thousand amperes, which can either be westward or eastward, depending on the direction of the electric field. (6) The induced electric field inside the arc is almost constant and different from outside. These results are consistent with the observational results.

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Measurement of auroral Birkeland currents and energetic particle fluxes

Cited by 47 publications

References 8 publications

Improved Open Boundary Model for Plasma Particle Simulations

Improved Open Boundary Model for Plasma Particle Simulations

Identifications of the polar cap boundary and the auroral belt in the high-altitude magnetosphere: A model for field-aligned currents

A theory of quiet auroral arcs

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