Zoom Link: https://uiowa.zoom.us/j/99600097237

Meeting ID: 996 0009 7237

Physics & Astronomy Colloquium

Speaker: Professor Jan Egedal; Department of Physics; University of  Wisconsin

Title: Magnetic Reconnection: A Celestial Phenomenon in the Laboratory

Abstract: The Terrestrial Reconnection Experiment (TREX) [1] executed in the Big Red Ball at the University of Wisconsin 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 talk I will review some of the outstanding issues in magnetic reconnection, but then turn to important recent discoveries. In TREX, upgrades to the reconnection drive now allows us to access are more fully collisionless regime in which 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 scenarios are important to a range of systems including the interaction of stellar winds with planetary magnetospheres. We also observe a shock interface to form between the supersonically driven plasma inflow; a region of magnetic flux pileup permits the normalized reconnection rate to self-regulate to a value where the inflow speed is about 50% of the Alfvenic outflow speeds observed in the reconnection exhaust, weakly dependent on the system size.

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

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