Dynamics of single-particle orbits during substorm expansion phase

Journal Article · Sat Dec 01 04:00:00 EST 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA12p20853· OSTI ID:5377073

Delcourt, D C; Pedersen, A ^[1]; Sauvaud, J A ^[2]

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1. European Space Research and Technology Center, Noordwijk (Netherlands)
2. Centre National de la Recherche Scientifique, Toulouse (France)

Features of ion trajectories during taillike to dipolelike magnetic transitions are examined by means of three-dimensional particle codes. It is demonstrated that the large electric fields induced by the collapse of the geomagnetic tail result in enhanced earthward convection of the midtail ({approximately}10 R{sub E}) magnetospheric populations. It is shown that the particle motion is controlled, to a major extent, by drifts that are negligible in steady state, namely, (1) in the direction parallel to the magnetic field, a centrifugal acceleration related to the rapid E {times} B transport, which can account for creation of new high-altitude mirror points, (2) perpendicularly to the magnetic field, a drift of polarization which possibly yields frozen-in violation and transient breaking of the first adiabatic invariant. In this latter case the simulations emphasize that the guiding center validity is at stake depending upon particle mass and/or charge state and allow the authors to distinguish three types of ion behavior (adiabatic, nonadiabatic and gyrophase dependent, nonadiabatic and gyrophase independent) according to injection depth in the plasma sheet. Also, systematic orbit calculations show that the low-latitude populations are most affected by the collapse of the geomagnetic tail and reveal possible dramatic (from hundreds of eV up to hundreds of keV) accelerations of the particles. These trajectory results are of relevance to explain various storm time signatures at geosynchronous altitudes and provide a populating mechanism for the ring current region.

• OSTI ID: 5377073
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:A12; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCELERATION
CHARGED PARTICLES
COMPUTER CODES
CONVECTION
CURRENTS
DYNAMICS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
ELECTRIC FIELDS
ENERGY TRANSFER
EXPANSION
GUIDING-CENTER APPROXIMATION
HEAT TRANSFER
ION DRIFT
IONS
MAGNETIC BAYS
MAGNETOTAIL
MASS TRANSFER
MECHANICS
PLASMA DRIFT
PLASMA SHEET
STEADY-STATE CONDITIONS
TRAJECTORIES