scholarly journals Properties of large electric fields in the plasma sheet at 4-7REmeasured with Polar

2001 ◽  
Vol 106 (A4) ◽  
pp. 5779-5798 ◽  
Author(s):  
A. Keiling ◽  
J. R. Wygant ◽  
C. Cattell ◽  
M. Johnson ◽  
M. Temerin ◽  
...  
Keyword(s):  
Electric Fields ◽  
Plasma Sheet

scholarly journals Magnetic field configuration and field-aligned acceleration of energetic ions during substorm onsets

2001 ◽  
Vol 19 (9) ◽  
pp. 1089-1094 ◽  
Author(s):  
A. Korth ◽  
Z. Y. Pu
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Plasma Sheet ◽  
Field Configuration ◽  
Local Magnetic Field ◽  
Magnetospheric Configuration And Dynamics ◽  
Night Side ◽  
Field Lines ◽  
Synchronous Orbit ◽  
Substorm Onsets

Abstract. In this paper, we present an interpretation of the observed field-aligned acceleration events measured by GEOS-2 near the night-side synchronous orbit at substorm onsets (Chen et al., 2000). We show that field-aligned acceleration of ions (with pitch angle asymmetry) is closely related to strong short-lived electric fields in the Ey direction. The acceleration is associated with either rapid dipolarization or further stretching of local magnetic field lines. Theoretical analysis suggests that a centrifugal mechanism is a likely candidate for the parallel energization. Equatorward or anti-equatorward energization occurs when the tail current sheet is thinner tailward or earthward of the spacecraft, respectively. The magnetic field topology leading to anti-equatorward energization corresponds to a situation where the near-Earth tail undergoes further compression and the inner edge of the plasma sheet extends inwards as close as the night-side geosynchronous altitudes.Key words. Magnetospheric physics (magnetospheric configuration and dynamics; plasma sheet; storms and sub-storms)

scholarly journals A physical mechanism producing suprathermal populations and initiating substorms in the Earth's magnetotail

2008 ◽  
Vol 26 (6) ◽  
pp. 1617-1639 ◽  
Author(s):  
D. V. Sarafopoulos
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Plasma Sheet ◽  
Physical Mechanism ◽  
Energetic Particles ◽  
Dimensional Structure ◽  
Magnetospheric Substorms ◽  
Physical Description ◽  
Fundamental Building Block ◽  
Field Lines

Abstract. We suggest a candidate physical mechanism, combining there dimensional structure and temporal development, which is potentially able to produce suprathermal populations and cross-tail current disruptions in the Earth's plasma sheet. At the core of the proposed process is the "akis" structure; in a thin current sheet (TCS) the stretched (tail-like) magnetic field lines locally terminate into a sharp tip around the tail midplane. At this sharp tip of the TCS, ions become non-adiabatic, while a percentage of electrons are accumulated and trapped: The strong and transient electrostatic electric fields established along the magnetic field lines produce suprathermal populations. In parallel, the tip structure is associated with field aligned and mutually attracted parallel filamentary currents which progressively become more intense and inevitably the structure collapses, and so does the local TCS. The mechanism is observationally based on elementary, almost autonomous and spatiotemporal entities that correspond each to a local thinning/dipolarization pair having duration of ~1 min. Energetic proton and electron populations do not occur simultaneously, and we infer that they are separately accelerated at local thinnings and dipolarizations, respectively. In one example energetic particles are accelerated without any dB/dt variation and before the substorm expansion phase onset. A particular effort is undertaken demonstrating that the proposed acceleration mechanism may explain the plasma sheet ratio Ti/Te≈7. All our inferences are checked by the highest resolution datasets obtained by the Geotail Energetic Particles and Ion Composition (EPIC) instrument. The energetic particles are used as the best diagnostics for the accelerating source. Near Earth (X≈10 RE) selected events support our basic concept. The proposed mechanism seems to reveal a fundamental building block of the substorm phenomenon and may be the basic process/structure, which is now missing, that might help explain the persistent, outstanding deficiencies in our physical description of magnetospheric substorms. The mechanism is tested, checked, and found consistent with substorm associated observations performed ~30 and 60 RE away from Earth.

Geotail observations of spiky electric fields and low-frequency waves in the plasma sheet and plasma sheet boundary

1994 ◽  
Vol 21 (25) ◽  
pp. 2987-2990 ◽  
Author(s):  
C. Cattell ◽  
F. Mozer ◽  
K. Tsuruda ◽  
H. Hayakawa ◽  
M. Nakamura ◽  
...  
Keyword(s):  
Electric Fields ◽  
Plasma Sheet ◽  
Low Frequency ◽  
Low Frequency Waves

scholarly journals Cluster EDI convection measurements across the high-latitude plasma sheet boundary at midnight

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1669-1681 ◽  
Author(s):  
J. M. Quinn ◽  
G. Paschmann ◽  
R. B. Torbert ◽  
H. Vaith ◽  
C. E. McIlwain ◽  
...  
Keyword(s):  
Electric Fields ◽  
High Latitude ◽  
Plasma Sheet ◽  
Boundary Region ◽  
Electron Drift ◽  
Polar Cap ◽  
Static Structure ◽  
Boundary Crossings ◽  
Instruments And Techniques ◽  
Using Data

Abstract. We examine two crossings of three Cluster satellites from the polar cap into the high-latitude plasma sheet at midnight local time, using data from the Electron Drift Instrument (EDI). EDI measures the full electron drift velocity in the plane perpendicular to the magnetic field for any field and drift directions. The context of the measured convection velocities is established by their relation to the intense enhancements in 1 keV electrons, also measured by EDI, as the satellites move from the polar cap into the plasma sheet boundary. In both cases presented here, the cross B convection in the polar cap is anti-sunward (toward the nightside plasma sheet) with a small duskward component. As the satellites enter the plasma sheet boundary region, the dawn-dusk convective flow component reverses its sign, and the flow in the meridianal plane (toward the center of the plasma sheet) drops substantially. The relatively stable convection in the polar cap becomes highly variable as the PSBL is encountered. The timing and sequence of the boundary crossings by the Cluster satellites are consistent with a relatively static structure on a time scale of the few minutes in satellite separations. In one of the two events, the plasma sheet boundary has a spatially separate structure that is crossed by the satellites before entering the plasma sheet.Key words. Magnetospheric physics (electric fields; magnetopause, cusp and boundary layers; instruments and techniques)

scholarly journals <i>Introduction</i>: The Equator-S mission

1999 ◽  
Vol 17 (12) ◽  
pp. 1499-1502 ◽  
Author(s):  
G. Haerendel ◽  
R. B. Torbert ◽  
H. Höfner
Keyword(s):  
Electric Fields ◽  
Plasma Sheet ◽  
Electron Beams ◽  
Plasma Environment ◽  
Outer Magnetosphere ◽  
Morning Sector ◽  
Hot Plasma ◽  
Operational Life ◽  
Successful Testing

Abstract. In spite of its short operational life of only five months, the major goals of the Equator-S mission were fulfilled, except that its contribution to the ISTP science is restricted to the morning sector of the outer magnetosphere. A set of twelve papers following this introduction is a first documentation of the achievements. They span from the successful testing and operation of the most advanced and complex way of measuring electric fields in a hot plasma environment by means of electron beams, to various investigations at or near the equatorial magnetopause and in the plasma sheet.

scholarly journals Large-amplitude electric fields associated with bursty bulk flow braking in the Earth's plasma sheet

2015 ◽  
Vol 120 (3) ◽  
pp. 1832-1844 ◽  
Author(s):  
R. E. Ergun ◽  
K. A. Goodrich ◽  
J. E. Stawarz ◽  
L. Andersson ◽  
V. Angelopoulos
Keyword(s):  
Electric Fields ◽  
Plasma Sheet ◽  
Large Amplitude ◽  
Bulk Flow ◽  
Bursty Bulk Flow

scholarly journals Substorm dynamics revealed by ground observations of two-dimensional auroral structures on 9 October 2000

2005 ◽  
Vol 23 (12) ◽  
pp. 3599-3613 ◽  
Author(s):  
J. Liang ◽  
E. F. Donovan ◽  
G. J. Sofko ◽  
T. Trondsen
Keyword(s):  
Electric Fields ◽  
Time Resolution ◽  
Plasma Sheet ◽  
Wave Activity ◽  
High Time ◽  
Geosynchronous Orbit ◽  
High Time Resolution ◽  
Two Dimensional ◽  
Mode Instability ◽  
The Third

Abstract. Multi-instrument observations of a small substorm event on 9 October 2000 provide, with high time resolution, two-dimensional information about substorm dynamics. A sequence of three optical intensifications, each associated with a Pi2 burst, were found, in which the third auroral intensification marked the onset of a small substorm. All three intensifications originated close to midnight, but evolved progressively eastward. Within each of the three optical intensifications, a few azimuthally-spaced patches appeared, the first one near midnight and the subsequent patches successively eastward in the postmidnight sector, providing evidence for drift wave activity in the near-geosynchronous-orbit plasma sheet (NGOPS). The SuperDARN measurements reveal the development of eastward electric fields at NGOPS latitude within each Pi2 burst interval. These observations can be interpreted as supporting the drift-Alfvén-ballooning (DAB) mode instability and its role in substorm expansion at NGOPS.

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