title: Decay of MHD-scale Kelvin-Helmholtz vortices mediated by parasitic electron dynamics.
abstract: We have simulated nonlinear development of MHD-scale Kelvin-Helmholtz (KH) vortices by a two-dimensional two-fluid system including finite electron inertial effects. In the presence of moderate density jump across a shear layer, in striking contrast to MHD results, MHD KH vortices are found to decay by the time one eddy turnover is completed. The decay is mediated by smaller vortices that appear within the parent vortex and stays effective even when the shear layer width is made larger. It is shown that the smaller vortices are basically of MHD nature while the seeding for these is achieved by the electron inertial effect. Application of the results to the magnetotail boundary layer is discussed.
authors.affiliation: Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551, Japan.
authors.forename: T K M
authors.initials: TK
authors.lastname: Nakamura
authors.forename: D
authors.initials: D
authors.lastname: Hayashi
authors.forename: M
authors.initials: M
authors.lastname: Fujimoto
authors.forename: I
authors.initials: I
authors.lastname: Shinohara