Relaxation and merging flux ropes and 3D effects in the Reconnection Scaling Experiment at LANL

Magnetic structures are embedded in astrophysical, space, solar and laboratory plasmas. The dynamics and relaxation of these plasmas can involve flows, changes in topology, magnetic reconnection, plasma heating, and dissipation of magnetic energy. This complex behavior is intrinsically three-dimensional (3D). Current-carrying magnetic flux ropes are the fundamental building blocks for many of these cases. At Los Alamos National Laboratory, we have an experimental realization of this model. The Reconnection Scaling Experiment (RSX) is a unique facility that can create multiple current-carrying flux ropes in an MHD experiment. Plasma guns are used to inject magnetic helicity into plasma columns. We show 3D structure with camera views, along with magnetic, electric, and particle probe data. Experiments in the presence of a strong guide magnetic field (Bz/Brcxn>10) show the formation of a current sheet and electron heating during the coalescence of two flux ropes. Computed simulations of the interactions of two current ropes are shown of that predict many of the experimental characteristics. A density wave structure that propagates opposite to the current is measured in the current sheet with wavelength and speed that are consistent with a kinetic Alfven wave. The current channels acquire angular momentum and rotate about each other developing helical structures, both individually and jointly. Parallel pressure gradients (a 3D effect) appear to be an important term in the Ohm's Law.status: publishe