HR: 1330h
AN: SM52B-0588    [PDF]
TI: Three-dimensional MHD Simulations of Kelvin-Helmholtz Instability in a Tail-flank Like Geometry
AU: * Hashimoto, C
EM: chika-h@geo.titech.ac.jp
AF: Earth and Planetary Sci., TITech, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
AU: TanDokoro, R
EM: rtdokoro@geo.titech.ac.jp
AF: Earth and Planetary Sci., TITech, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
AU: Fujimoto, M
EM: fujimoto@geo.titech.ac.jp
AF: Earth and Planetary Sci., TITech, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
AB: In order to understand the nature of the Kelvin-Helmholtz (K-H) instability in the tail-flank situation, we have been performing three-dimensional MHD simulations of the K-H instability. We have obtained the results for the two basic configurations, one in which the magnetic field is uniform and perpendicular to the velocity flow (transverse case) and the other where the field is uniform and parallel to the flow (parallel case). We have set the density variation that makes an unstable layer of finite thickness to be located between two stable regions. Whether the vigorous growth of the K-H instability is available or not would depend on the thickness of the unstable layer H. Indeed, for the transverse case, the critical thickness below which no growth is available is about a half of the wavelength of the fastest growing mode. However, the growth rate obtained even when the thickness is as small as 1/3 of the wavelength is almost unaffected for the parallel case. These results have the following implications to the magnetotail flank situaition. The thickness H mentioned above corresponds to the thickness of the plasma sheet. The magnetosheath magnetic field has substantial component transverse to the velocity flow and the magnetospheric field is mostly parallel to the flow. It is the copuling between the sheath field and the thickness of the plasma sheet that gives rise to three-dimensional effects. When the shear flow at the tail-flank give rise to the K-H instability, the magnetosheath magnetic field lines will be bent and their tips will intrude into the plasma sheet. The strength of magnetosheath field and the plasma sheet thickness H should control the stability and the non-linear phase of the K-H instability. The parameter space where significant effects of the K-H instability are available will be shown and it is compared with the tail-flank parameters.
DE: 2728 Magnetosheath
DE: 2748 Magnetotail boundary layers
DE: 2784 Solar wind/magnetosphere interactions
DE: 5737 Magnetospheres (2756)
DE: 7843 Numerical simulation studies
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting