Magnetohydrodynamic modeling of two-dimensional reconnection in the Magnetic Reconnection Experiment

A two-dimensional magnetohydrodynamics (MHD) code is used to investigate the dynamical evolution of driven reconnection in the Magnetic Reconnection Experiment (MRX) [M. Yamada et al., Phys. Plasmas 7, 1781 (2000)]. The initial conditions and dimensionless parameters of the simulation are set to be similar to the experimental values. Many features of the time-evolution of magnetic configurations for both co- and counter-helicity reconnection in MRX are successfully reproduced in the framework of resistive MHD. The resistive MHD model is then augmented by the addition of a "model Hall" term to begin to assess the importance of two-fluid physics in the experiment. The effective decoupling of the ion fluid from the reconnecting magnetic field due to the model Hall term is shown to be important during the early dynamic X-phase of MRX reconnection, while effectively negligible during the late "steady-state" Y-phase, when plasma heating takes place. These results are consistent with the available experimental evidence. Based on simple symmetry considerations, an experiment to directly measure the Hall effect in MRX configuration is proposed and numerical evidence for the expected outcome is given. (C) 2003 American Institute of Physics.