  Using a three-dimensional magnetohydrodynamic model, we simulate the magnetic
reconnection in a single current sheet. We assume a finite guide field, a
random perturbation on the velocity field and uniform resistivity. Our model
enhances the reconnection rate relative to the classical Sweet-Parker model in
the same configuration. The efficiency of magnetic energy conversion is
increased by interactions between the multiple tearing layers coexisting in the
global current sheet. This interaction, which forms a positive-feedback system,
arises from coupling of the inflow and outflow regions in different layers
across the current sheet. The coupling accelerates the elementary reconnection
events, thereby enhancing the global reconnection rate. The reconnection
establishes flux tubes along each tearing layer. Slow-mode shocks gradually
form along the outer boundaries of these tubes, further accelerating the
magnetic energy conversion.Such positive-feedback system is absent in
two-dimensional simulation, three-dimensional reconnection without a guide
field and a reconnection under a single perturbation mode. We refer to our
model as the "shock-evoking positive-feedback" model.
