Roles of plasma instabilities and particle kinetic 
effects in collisionless driven reconnection

Ritoku Horiuchi, Hiroaki Ohtani, Akihiro Ishizawa, and Toseo Moritaka

 Roles of plasma instabilities and particle kinetic effects in collisionless 
reconnection are investigated by means of three-dimensional full particle 
simulations based on an open boundary model. In the early stage of 
simulation non-ideal effects such as inertia effect and meandering effect 
breaks the frozen-in condition of magnetic field in the central current 
region, and it leads to the penetration of the driving electric field into 
the current sheet and the excitation of  collisionless reconnection. The 
current sheet is split as a result of collisionless reconnection, and thus 
small islands appear in the downstream. When the magnetic islands move out 
though the boundary, the system relaxes into a quasi-steady state.  A 
low-frequency electromagnetic (EM) instability, called drift-kink 
instability (DKI), is excited near the central region in this quasi-steady 
state. The electron flow crossing the neutral sheet is generated by the 
excited EM waves. This flow operates as resistivity on the equilibrium 
current flowing along the neutral sheet. This mode has a peak in the 
frequency spectrum near the ion cyclotron frequency. Furthermore, the width 
of current sheet is comparable to the ion meandering amplitude. It is 
concluded that the DKI can be a cause of anomalous resistivity in the thin 
current sheet and the ion dynamics is a key process to control the anomalous 
resistivity in quasi-steady state.