HR: 1330h
AN: SM23B-12    [Abstracts]
TI: Hysteresis and the Onset of Fast Magnetic Reconnection
AU: * Cassak, P A
EM: pcassak@glue.umd.edu
AF: University of Maryland, Institute for Research in Electronics and Applied Physics, Energy Research Facility, Bldg. #223, Paint Branch Drive, College Park, MD 20742 United States
AU: Shay, M A
EM: shay@Glue.umd.edu
AF: University of Maryland, Institute for Research in Electronics and Applied Physics, Energy Research Facility, Bldg. #223, Paint Branch Drive, College Park, MD 20742 United States
AU: Drake, J F
EM: drake@plasma.umd.edu
AF: University of Maryland, Institute for Research in Electronics and Applied Physics, Energy Research Facility, Bldg. #223, Paint Branch Drive, College Park, MD 20742 United States
AB: Magnetic reconnection is vastly different depending on the collisionality of the system in question. Collisionless (Hall-mediated) reconnection is fast, with Alfvenic reconnection rates, while collisional (resistive MHD) reconnection is much slower. The transition between the two with varying resistivity may be important for understanding the onset of magnetic reconnection in physical systems such as solar eruptions and laboratory fusion experiments. We investigate the transition using basic theoretical arguments, and provide support using two-fluid numerical simulations. We show that, for intermediate values of the resistivity, the reconnection is bistable, i.e., the system can relax to either of the two configurations depending on the history of the system. We map the hysteresis curve and demonstrate that the transition from collisional to collisionless reconnection is catastrophic. We present a scaling analysis for the resistivities at which transitions occur and compare the predictions to parameters in the solar corona and for a sawtooth crash.
DE: 7835 Magnetic reconnection
SC: SPA-Magnetospheric Physics [SM]
MN: 2005 Joint Assembly