Global dynamics and rapid collapse of an isolated current-sheet system enclosed by free boundaries
Abstract
The self-consistent behavior of an isolated current-sheet system enclosed by free boundaries is numerically studied in the framework of magnetohydrodynamics. Initiated by a disturbance, the middle current sheet drastically collapses into a thin layer in a collisionless plasma. It is argued that an anomalous resistance should limit the extreme current concentration. When the current sheet, initially of width 2L, becomes thin, an anomalous resistivity η is introduced that increases with the relative electron-ion drift velocity ‖VD‖ when ‖VD‖ exceeds a threshold value VC. It is found that, when the reconnection flow has just been coupled to the anomalous resistivity, the reconnection growth rate [normalized by (L/VA)-1 ] becomes extremely large and scales as (∂η/∂‖VD‖)0.6V2.2C (normalization is based on the initial configuration); accordingly, the fast reconnection mechanism is set up on a short time scale and leads to the rapid collapse of the system at large. The initial growth of the fast reconnection is shown to be in good agreement with the underlying physical mechanism of the modified tearing instability.
- Publication:
-
Physics of Fluids
- Pub Date:
- November 1986
- DOI:
- 10.1063/1.865797
- Bibcode:
- 1986PhFl...29.3659U
- Keywords:
-
- Collisionless Plasmas;
- Current Sheets;
- High Temperature Plasmas;
- Plasma Dynamics;
- Plasma Layers;
- Boundary Value Problems;
- Drift Rate;
- Free Boundaries;
- Magnetic Field Reconnection;
- Plasma Physics