Magnetic reconnection in collisionless plasmas: Prescribed fields

Journal Article · Thu Nov 01 00:00:00 EST 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA11p18833· OSTI ID:5046397

Burkhart, G R ^[1]; Drake, J F ^[2]; Chen, J ^[3]

---

1. Science Applications International Corp., McLean, VA (United States)
2. Univ. of Maryland, College Park (United States)
3. Naval Research Lab., Washington, DC (United States)

The structure of the dissipation region during magnetic reconnection in collisionless plasma has been investigated. Particles are injected onto a computational grid, their orbits are integrated, and the moments of the distribution function are stored. The structure of the dissipation region depends on only two variables: a normalized reconnection electric field (E) and the opening angle {theta} of the separatrices of the magnetic field. An important conclusion of the work is that there is no linear relationship between the current sheet velocity v{sub y} and the electric field. For a small normalized electric field the maximum v{sub y} is localized away from the x line, is diamagnetic in origin, and is independent of (E) as (E) {yields} 0. For a large normalized electric field the effective life-time of particles in the reconnection region scales as (E){sup {minus}1/3} and v{sub y} {proportional to} (E){sup 2/3}. In this limit, particles are ejected from the reconnection region as high-velocity, gyrophase-bunched beams. These beams produced an irregular filamentary current distribution in the outflow region. The beams which are ejected along the center of the outflow region are eventually trapped by the magnetic field while the beams ejected just downstream from the separatrix continue to move with high velocity out of the comuptational region. Over the entire range of (E), significant temperature anisotropies are produced, with T{sub {perpendicular}} < T{sub {parallel}} in the inflow region and T{sub {perpendicular}} >> T{sub {parallel}} in the outflow region. Implications of the results for understanding magnetic reconnection in magnetospheric plasma and the source of energetic particles measured in the plasma sheet boundary layer and in explaining recent observations of fine scale magnetic turbulence in the central plasma sheet are discussed.

• OSTI ID: 5046397
• Journal Information: Journal of Geophysical Research; (United States), Vol. 95:A11; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COLLISIONLESS PLASMA
MAGNETIC RECONNECTION
EARTH MAGNETOSPHERE
ANISOTROPY
COLD PLASMA
DISTRIBUTION FUNCTIONS
ELECTRIC FIELDS
ENERGY LOSSES
MAGNETOHYDRODYNAMICS
PLASMA SHEET
EARTH ATMOSPHERE
FLUID MECHANICS
FUNCTIONS
HYDRODYNAMICS
LOSSES
MECHANICS
PLASMA
640201* - Atmospheric Physics- Auroral
Ionospheric
&amp; Magetospheric Phenomena