The coalescence instability in collisionless plasmas
- Department of Physics and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90024-1547 (United States)
The process whereby magnetic island structures tend to merge into larger units is known as magnetic island coalescence. This coalescence process is investigated for the case of a collisionless plasma by means of two-dimensional particle simulations. The pairwise merging of a preformed island chain leads to a gentle redistribution of the density and current density profiles. The linear growth rates substantially exceed the magnetohydrodynamic (MHD) values for {rho}/{lambda}{ge}0.1, where {rho} is the asymptotic ion gyroradius and {lambda} is the current sheet half-thickness. The nonlinear evolution of the collisionless tearing instability in a long system is found to lead to a much more violent coalescence process resulting in the formation of a vacuum X region. This stage is characterized by enhanced growth rates for the long-wavelength modes that exceed the maximum linear tearing growth rate, super-Alfvenic flows away from the reconnection X line, substantial bulk heating in the parallel direction, and the formation of energetic particle tails in the direction of the inductive electric field.
- OSTI ID:
- 7259096
- Journal Information:
- Physics of Fluids B; (United States), Journal Name: Physics of Fluids B; (United States) Vol. 4:10; ISSN 0899-8221; ISSN PFBPE
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
700340* -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
COALESCENCE
COLLISIONLESS PLASMA
CURRENT DENSITY
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
INSTABILITY GROWTH RATES
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC ISLANDS
MAGNETOHYDRODYNAMICS
MECHANICS
PLASMA
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PLASMA MICROINSTABILITIES
PLASMA SIMULATION
SIMULATION
TEARING INSTABILITY