Structure of the dayside reconnection layer in resistive MHD and hybrid models

Journal Article · Mon Mar 01 04:00:00 EST 1993 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JA02363· OSTI ID:6873336

Lin, Y; Lee, L C ^[1]

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1. Univ. of Alaska, Fairbanks (United States)

The structure of reconnection layer at the Earth's dayside magnetopause is studied based on one-dimensional simulations for the evoluation of an initial current sheet. A resistive MHD code and a hybrid code are used in simulations. Initially, the magnetopause current sheet separates two uniform plasma regions: magnetosheath (high plasma density and low magnetic field) and magnetosphere (low plasma density and high magnetic field). In MHD simulations, it is found that steady intermediate shock time-dependent intermediate shock (TDIS), Alfven wave pulse, slow shock, slow expansion wave, or contact discontinuity can be formed as a result of magnetic reconnection. The current density in the magnetopause-boundary layer region is mainly concentrated at the intermediate shock on the the magnetosheath side. High-speed flow is observed in the boundary layer. The Alfven wave pulse, which propagates to the magnetosphere, is found is have a large amplitude in plasma flow speed. In hybrid simulations, the reconnection layer has striking differences from that in MHD simulations: (1) Because of the mixing of hot magnetospheric plasma and cold magnetosheath plasma along magnetic field lines, the contact discontinuity does not appear in the reconnection layer. (2) In general cases, the TDIS evolves quickly to a steady rotational discontinuity with a constant width. (3) No clear shock front can be identified for the slow shock, and the slow expansion wave is strongly modified as compared with that in the MHD simulations. (4) The boundary layer is a transition region between the magnetosheath and the magnetosphere with a mixing of plasmas from the two sides. (5) A decrease in T[sub [perpendicular]]/T[sub [parallel]] is observed in the boundary layer. These results indicate that in general cases rotational discontinuities bound the reconnection layer at the dayside magnetopause. 36 refs., 15 figs.

• DOE Contract Number: FG06-86ER13530
• OSTI ID: 6873336
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 98:A3; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

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71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPUTERIZED SIMULATION
CURRENT DENSITY
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
EXPANSION
FLUID MECHANICS
HYDRODYNAMICS
MAGNETIC FIELDS
MAGNETIC RECONNECTION
MAGNETOHYDRODYNAMICS
MAGNETOPAUSE
MAGNETOSHEATH
MECHANICS
ONE-DIMENSIONAL CALCULATIONS
PLASMA
PLASMA DENSITY
PLASMA SHEET
SIMULATION