Long time scale evolution of collisionless driven reconnection in a two-dimensional open system

Long time scale evolution of collisionless driven reconnection in an open system is investigated by means of two-dimensional full particle simulation based on an open boundary model. Collisionless reconnection is externally driven by the plasma inflow, which is mainly controlled by two key parameters of an external driving electric field, i.e., the strength E-0 and the early nonuniformity scale x(d). The strength E-0 controls reconnection rate, while the scale x(d) controls the current layer shape and thus the magnetic-field configuration. It is found that the dynamical behavior of collisionless reconnection is sensitive to x(d) and less to E-0 in our simulation parameter range. In the small x(d) case, the system evolves toward a steady state in which the reconnection rate is balanced with the external driving field E-0. As x(d) increases, the reconnection evolution exhibits an intermittent phenomenon because of the frequent excitation of magnetic islands near the original X point. (C) 2001 American Institute of Physics.