Experimental study of the Hall effect and electron diffusion region during magnetic reconnection in a laboratory plasma

The Hall effect during magnetic reconnection without an external guide field has been extensively studied in the laboratory plasma of the Magnetic Reconnection Experiment [M. Yamada et al., Phys. Plasmas 4, 1936 (1997)] by measuring its key signature, an out-of-plane quadrupole magnetic field, with magnetic probe arrays whose spatial resolution is on the order of the electron skin depth. The in-plane electron flow is deduced from out-of-plane magnetic field measurements. The measured in-plane electron flow and numerical results are in good agreement. The electron diffusion region is identified by measuring the electron outflow channel. The width of the electron diffusion region scales with the electron skin depth (∼5.5–7.5c∕ωpe) and the peak electron outflow velocity scales with the electron Alfven velocity (∼0.12–0.16VeA), independent of ion mass. The measured width of the electron diffusion region is much wider and the observed electron outflow is much slower than those obtained in 2D numerical simulati...