Nonlinear evolution of double tearing mode in Hall magnetohydrodynamics

Nonlinear evolution of a double tearing mode for different plasma resistivities (eta) and ion inertial lengths (d(i)) is investigated using Hall magnetohydrodynamics simulations. In the Hall dominant regime, the magnetic field configuration in the reconnection region evolves from Y-type to X-type geometry, which leads to fast reconnection in the nonlinear growth phase. The maximum growth rate of total kinetic energy of plasma gamma(max) in the explosive growth phase is found to have a d(i)(2/5)eta(1/10) scaling and the maximum total kinetic energy (E-k)(max) scales as d(i)(4/5). In the regime with weak Hall effect, it is found that the elongated thin current sheet formed in the early phase is broken into two X-points, forming a magnetic island in the late stage, instead of shrinking to an X-type geometry.