Multiple X line reconnection: 3. A particle simulation of flux transfer events

Open Access
Publisher Website
Google Scholar
Abstract
The multiple X line reconnection process, which was proposed by Lee and Fu to explain the flux transfer events observed at the dayside magnetopause, is studied by computer simulations based on a two‐dimensional magnetostatic particle code. A driven boundary condition is applied at the two sides of the simulation domain with an incoming plasma flow while a free boundary condition is used at the other two sides with an outflow. Repeated formation and convection of magnetic islands are observed in the simulation. Magnetic islands with various sizes are observed. Superthermal ions of energy 5–50 keV, with an energy spectrum f(E)∼E−1.9, are generated during the multiple X line reconnection process. It is found that the power spectrum of the normal magnetic field is given by a power law PB ∼ k−0.6, where k is the wave number. The convection speed of magnetic islands may exceed the Alfvén speed. The recurrence time of magnetic islands is found to be τ ≃ 100/ΩRo, where Ω is the ion gyrofrequency, Ro = V1/VA, V1 is the imposed inflow speed, and VA is the Alfvén speed. Our results are consistent with satellite observations of flux transfer events.