Steady Hall Magnetohydrodynamics Near a X-type Magnetic Neutral Line

Hall magnetohydrodynamics (MHD) properties near a two-dimensional (2D) X-type magnetic neutral line in the steady state are considered. Upon considering the steady-state as the asymptotic limit of the corresponding time-dependent problem and using a rigorous development, Hall effects are shown to be or not to be able to sustain the hyperbolicity of the magnetic field (and hence a more open X-point configuration) near the neutral line depending on the initial conditions. The heuristic development misses this subtle connection of the steady state with the corresponding time-dependent problem and predicts only an elongated current-sheet configuration (as in resistive MHD). However, the heuristic development turns out to be useful in providing insight into the lack of dependence of the reconnection rate on the mechanism breaking the frozen-in condition of the magnetic field lines. The latter result can be understood in terms of the ability of the ions and electrons to transport equal amounts of magnetic flux per unit time out of the reconnection region. ∗Permanent Address: University of Central Florida, Orlando, FL 32816-1364