Numerical simulation of magnetic reconnection and plasmoid dynamics in the geotail

Abstract

The time evolution of the geotail is represented by a set of single fluid magnetohydrodynamic (MHD) equations. The initial equilibrium is allowed to be destroyed by a finite, but very small electric resistivity, so that the fluid is still an almost ideal MHD system. The subsequent evolution of the geotail is investigated by a two-dimensional numerical code. The onset of reconnection and formation of magnetic island-like structures called plasmoids are reproduced. The velocity pattern and the size of plasmoid are investigated under different initial conditions and are compared with actual observations in space.