Topological Considerations in an Experiment on Locating Where Fully Three Dimensional Reconnection Occurs and Ion Energization Within It

Magnetic flux ropes are bundles of twisted magnetic fields and their associated currents. They are common on the surface of the sun (and presumably all other stars) and are observed to have a large range of sizes and lifetimes. Two "kink" unstable ropes are generated in a background plasma in the Large Plasma Device at UCLA. When they collide fully 3D magnetic reconnection occurs. In fully three dimensional reconnection the location(s) at which reconnection occurs are challenging to identify. In this experiment the time dependent magnetic fields, plasma flows, electron temperature, plasma density, and electric fields were measured at over 42,000 spatial positions requiring several million rope collision experiments. Magnetic field lines are followed in 3D and used to derive quasi-seperatrix layers (QSL), extended surfaces within which reconnection occurs. We have used additional topological quantities : the winding number, magnetic twist, writhe and helicity to calculate a new quantity, the reconnection activity (RA). The RA identifies sub-regions of magnetic field lines which are reconnecting that are not within the QSL. A small ion energy analyzer was used to measure the ion distribution function in the reconnection region at several angles with respect to the magnetic field. Heating and the formation of field aligned particle jets is observed.