3D EMHD reconnection in a laboratory plasma

Abstract

In a large laboratory plasma, reconnection of three-dimensional (3D) magnetic fields is studied in the parameter regime of electron magnetohydrodynamics (EMHD). The field topologies are spheromak-like with two-dimensional null lines and three-dimensional spiral null points. The relaxation of an initial vortex field by spontaneous reconnection is studied in the absence of boundary effects. Reconnection rates and energy conversion from fields to particles are measured. The frozen-in condition appears to be destroyed by viscous effects rather than inertia or collision. Finally, the non-driven merging of two EMHD spheromaks into a long-lived FRC is observed. These basic physics experiments demonstrate that reconnection is an important process in the parameter regime of unmagnetized ions, which is always encountered near absolute magnetic null points. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences.