Abstract
Magnetic reconnection is essentially a multi-scale phenomenon, driven by kinetic process in microscopic region and enabling explosive energy conversion from magnetic field energy to plasma kinetic energy in large area. It has been poorly understood how the kinetic process around the x-line connects to the magnetohydrodynamics (MHD) scale process in the reconnection downstream region. The present study has investigated the energy conversion process in the region far downstream of the x-line, by means of the particle-in-cell (PIC) simulation with the adaptive mesh refinement (AMR). The AMR-PIC model enables efficient kinetic simulation of multi-scale phenomena using dynamically adaptive meshes. It is found that the ion energy gain dominates in the reconnection region and is carried out mainly in the exhaust center rather than the exhaust boundaries. The simulation results suggest that the energy conversion process in collisionless magnetic reconnection is significantly different from that in the MHD reconnection model in which most energy conversion occurs at slow mode shocks formed at the exhaust boundaries.
Highlights
Magnetic reconnection is a natural energy converter that allows explosive energy release of the magnetic field energy into plasma kinetic energy
The magnetic dissipation driving the reconnection process takes place in a localized region formed around the x-line, while it has a significant impact on large-scale dynamics of the planetary magnetosphere, leading to the global change of the field line configuration and the global plasma convection
In association with the magnetic dissipation, the energy conversion occurs around the x-line [e.g., 7], so that the electrons obtain significant energy from the electric and magnetic field
Summary
Magnetic reconnection is a natural energy converter that allows explosive energy release of the magnetic field energy into plasma kinetic energy. The magnetic dissipation driving the reconnection process takes place in a localized region formed around the x-line, while it has a significant impact on large-scale dynamics of the planetary magnetosphere, leading to the global change of the field line configuration and the global plasma convection. The dissipation (i.e., the effective resistivity) around the x-line is caused by the transport of the electron momentum in the diffusion region scaled by the electron kinetic scales [1]. It is known that major amount of the energy released in reconnection goes to the ions that have a much larger mass than the electrons [e.g., 8]. The ion acceleration processes could be more important in the overall energy conversion process through magnetic reconnection
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