title: Role of Ion Kinetic Physics in the Interaction of Magnetic Flux Ropes.
abstract: To explain many natural magnetized plasma phenomena, it is crucial to understand how rates of collisionless magnetic reconnection scale in large magnetohydrodynamic (MHD) scale systems. Simulations of isolated current sheets conclude such rates are independent of system size and can be reproduced by the Hall-MHD model, but neglect sheet formation and coupling to MHD scales. Here, it is shown for the problem of flux-rope merging, which includes this formation and coupling, that the Hall-MHD model fails to reproduce the kinetic results. The minimum sufficient model must retain ion kinetic effects, which set the ion diffusion region geometry and give time-averaged rates that reduce significantly with system size, leading to different global evolution in large systems.
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: A
authors.initials: A
authors.lastname: Stanier
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: W
authors.initials: W
authors.lastname: Daughton
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: L
authors.initials: L
authors.lastname: Chacón
authors.affiliation: SciberQuest, Inc., Del Mar, California 92014, USA.
authors.forename: H
authors.initials: H
authors.lastname: Karimabadi
authors.affiliation: Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: J
authors.initials: J
authors.lastname: Ng
authors.affiliation: Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: Y-M
authors.initials: YM
authors.lastname: Huang
authors.affiliation: Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: A
authors.initials: A
authors.lastname: Hakim
authors.affiliation: Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: A
authors.initials: A
authors.lastname: Bhattacharjee