Magnetosheath-ionospheric plasma interactions in the cups/cleft 2. Mesoscale particle simulations

Journal Article · Mon Nov 01 04:00:00 EST 1993 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/93JA01744· OSTI ID:146565

Winglee, R M ^[1]; Menietti, J D ^[2]; Lin, C S ^[3]

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1. Univ. of Washington, Seattle, WA (United States)
2. Univ. of Iowa, Iowa City, IA (United States)
3. Southwest Research Institute, San Antonio, TX (United States)

Ionospheric plasma flowing out from the cusp can be an important source of plasma to the magnetosphere. One source of free energy that can drive this outflow is the injection of magnetosheath plasma into the cusp. Two-dimensional (three velocity) mesoscale particle simulations are used to investigate the particle dynamics in the cusp during southward interplanetary magnetic field. This mesoscale model self-consistently incorporates (1) global influences such as the convection of plasma across the cusp, the action of the mirror force, and the injection of the magnetosheath plasma, and (2) wave-particle interactions which produce the actual coupling between the magnetosheath and ionospheric plasmas. It is shown that, because the thermal speed of the electrons is higher than the bulk motion of the magnetosheath plasma, an upward current is formed on the equatorward edge of the injection region with return currents on either side. However, the poleward return currents are the stronger due to the convection and mirroring of many of the magnetosheath electrons. The electron distribution in this latter region evolves from upward directed streams to single-sided loss cones or possibly electron conics. The ion distribution also shows a variety of distinct features that are produced by spatial and/or temporal effects associated with varying convection patterns and wave-particle interactions. On the equatorward edge the distribution has a downflowing magnetosheath component and an upflowing cold ionospheric component due to continuous convection of ionospheric plasma into the region. Further poleward there is velocity filtering of ions with low pitch angles, so that the magnetosheath ions develop a ring-beam distribution and the ensuing wave instabilities generate downward ionospheric conics. These downward ionospheric components are eventually turned by the mirror force, leading to the production of upward conics at elevated energies throughout the region. 17 refs., 13 figs.

• Sponsoring Organization: USDOE
• OSTI ID: 146565
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A11 Vol. 98; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
COMPUTERIZED SIMULATION
EARTH MAGNETOSPHERE
INTERPLANETARY MAGNETIC FIELDS
IONOSPHERE
PLASMA DRIFT
PLASMA EXPANSION
POLAR CUSP