Magnetic reconnection in magnetotail and solar plasmas

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5225886

Wang, Xiaogang

The formation of current sheets which dominates the heating of the solar corona and the onset of substorms due to collisionless tearing instability in the magnetotail are investigated in the context of magnetic field line reconnection in space plasmas. In Chapters 2 and 3 of this thesis, the collisionless tearing instability and current disruption of the magnetotail are considered. The linear collisionless tearing instability, with wavelengths of the order of 10 R{sub E}, and with a growth rate {gamma} {approximately} 10{sup {minus}2}/sec, is identified as a possible mechanism for the growth phase of a substorm. The linear analysis is carried out in the presence of an equilibrium B{sub y}-field, neglected in other theories. The nonlinear theory of collisionless tearing mode is dominated by mode coupling effects. From the evolution equations for electro-magnetic field perturbations, the author derived a nonlinear growth rate by generalizing the boundary layer techniques of linear theory. He finds that the nonlinear growth is of the order of 1 sec, much faster than the linear growth. It is proposed that collisionless tearing modes provide a mechanism for current disruption observed by spacecrafts. The electrical field generated during the nonlinear evolution can cause particle acceleration in the earth-tail direction. His estimates indicate ion energies up to 0.7 MeV and electron energies up to 8.1 MeV, which is not inconsistent with the observations. In the Chapter 4 it is shown that current sheets can be formed in Parker's model of the solar corona in the presence of smooth photospheric flows, despite van Ballegooijen and Field's proof that in an ideal plasma current sheets doe not occur unless the boundary velocity field is discontinuous.

• Research Organization: Columbia Univ., New York, NY (United States)
• OSTI ID: 5225886
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
COLLISIONLESS PLASMA
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC FIELDS
HEATING
INSTABILITY
MAGNETIC RECONNECTION
MAGNETIC STORMS
MAGNETOTAIL
NONLINEAR PROBLEMS
PLASMA
PLASMA HEATING
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
SOLAR ATMOSPHERE
SOLAR CORONA
STELLAR ATMOSPHERES
STELLAR CORONAE
TEARING INSTABILITY