Force balance near an X line in a collisionless plasma
- Aerospace Corp., Los Angeles, CA (USA)
The authors investigate the balance of forces near an X line in a collisionless plasma having a reconnection electric field along the X line. Near an X line the generalized Ohm's law reduces to the electron momentum equation. They use a two-dimensional magnetic field model and apply a simplified model of particle motion to evaluate terms in this momentum equation. The results show that the gyroviscosity associated with off-diagonal elements of the pressure tensor can balance the electric field at and near the X line, as has recently been suggested by Dungey. Particle velocity moments do not become large at the X line, and they conclude that neither collisions nor wave turbulence are necessary for an electric field along an X line to be maintained. Gyroviscosity results from single-particle motion in the presence of the magnetic field gradients near the X line, but they find that large values for these gradients are not required. They find that conditions expected to occur in the distant geomagnetic tail yield reasonable values for the physical parameters associated with reconnection. However, the equations provide no actual constraints on parameters other than the requirement for force balance. Thus gyroviscosity does not impose restraints on the reconnection rate. The present application is to the geomagnetic tail, but the results should apply as well to collisionless reconnection in many situations.
- OSTI ID:
- 5378224
- Journal Information:
- Journal of Geophysical Research; (United States), Vol. 95:A12; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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Force balance near an X line along which E (dot) is less than 0
Force balance near an X line along which E. J < 0
Related Subjects
GENERAL PHYSICS
MAGNETOTAIL
MAGNETIC RECONNECTION
COLLISIONLESS PLASMA
DATA ANALYSIS
ELECTRIC FIELDS
ENERGY TRANSFER
GEOMAGNETIC FIELD
MASS TRANSFER
MATHEMATICAL MODELS
TURBULENCE
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
MAGNETIC FIELDS
PLASMA
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena