3D EMHD reconnection in a laboratory plasma

In a large laboratory plasma, reconnection of three-dimensional (3D) magnet ic fields is studied in the parameter regime of electron magnetohydrodynami cs (EMHD). The field topologies are spheromak-like with two-dimensional nul l lines and three-dimensional spiral null points. The relaxation of an init ial vortex field by spontaneous reconnection is studied in the absence of b oundary effects, Reconnection rates and energy conversion from fields to pa rticles are measured. The frozen-in condition appears to be destroyed by vi scous effects rather than inertia or collision. Finally, the non-driven mer ging of two EMHD spheromaks into a long-lived FRC is observed. These basic physics experiments demonstrate that reconnection is an important process i n the parameter regime of unmagnetized ions, which is always encountered ne ar absolute magnetic null points.