Collisionless reconnection in the Terrestrial Reconnection Experiment (TREX)

The newly developed Terrestrial Reconnection Experiment (TREX) [1] in the Wisconsin Plasma Physics Laboratory (WiPPL) [2] is optimized to study magnetic reconnection in a regime where Coulomb collisions between electrons and ions are sufficiently infrequent that kinetic effects in the electron dynamics are retained. In this fully collisionless regime electron pressure anisotropy develops and is fundamental to the structure of the electron diffusion region. The observed signatures of reconnection include narrow electron jets and current layers with widths down to the scale length of the electron skin depth, confirming previous results from fully kinetic simulations. Driven reconnection is important to a range of systems including the interaction of stellar winds with planetary magnetospheres. In our scenario the experimental rate of reconnection is surprisingly large, with inflow speeds to the reconnection region being similar to the Alfvenic outflow speeds observed in the reconnection exhaust. Consequently, the normalized reconnection rate, on the order of unity, is about an order of magnitude larger than those typically observed in undriven systems.

[1] J. Olson, et al., Phys. Rev. Lett {\bf 116}, 255001 (2016)

[2] C.B. Forest, et al., Jour. Plasma Phys., {\bf 81}, 345810501 (2015)