HR: 1330h
AN: SM52B-0592 [PDF]
TI: Stability and Structure of Superthin" Sheets: 2D and 3D Full Particle Simulations
AU: * Karimabadi, H
EM: homa@ece.ucsd.edu
AF: UCSD, Dept. of ECE, MC 0407, La Jolla, CA 92093-0407 United States
AU: Krauss-Varban, D
EM: varban@ece.ucsd.edu
AF: UCSD, Dept. of ECE, MC 0407, La Jolla, CA 92093-0407 United States
AU: Daughton, W
EM: daughton@lanl.gov
AF: Los Alamos National Laboratory, MSB 259, Los Alamos, NM 87544 United States
AU: Pritchett, P
EM: pritchet@physics.ucla.edu
AF: UCLA, Dept. of Physics, Los Angeles, CA 90095-1547 United States
AU: Omidi, N
EM: omidi@ece.ucsd.edu
AF: UCSD, Dept. of ECE, MC 0407, La Jolla, CA 92093-0407 United States
AB:
Current sheets are a central feature of magnetospheric structures and play a significant role in the transfer of plasma,
momentum and energy from the solar wind. Our recent hybrid (fluid electrons, kinetic ions) simulations for northward IMF
demonstrate that magnetospheric structures go through well defined transition points as the magnetic dipole strength is
increased in value. Further, for weak dipole fields, which may be relevant for asteroids and smaller planets, the
magnetopause takes the form of a very thin current layer with Ÿƒ/L ~ 7 where ŸƒŸnis the ion gyroradius and L is the current
sheet half-thickness. The properties of such thin current sheets are largely unknown. We have used linear kinetic theory as
well as 2D and 3D full particle simulations to study the structure and stability of such thin sheets. Some of the important
issues that we address include, (i) what is the lower limit of current sheet thickness in the presence of instabilities such
as the lower hybrid drift instability that will broaden the sheet? (ii) Can magnetic reconnection occur in this limit and
what form will it take? Thin sheets also enable us to settle important issues regarding the stability of thicker current
sheets observed at Earth. The study of such current sheets at has been difficult due to small growth rates, and many
important issues remain unresolved. Even using unrealistically small mass ratios, relevant simulations remain out of reach
of present computational capabilities. Through our study of thin sheets we will address issues that are of direct interest
to the EarthÝs magnetosphere, using realistic mass ratios. Examples include (i) nonlinear interaction of tearing and lower
hybrid drift instability and (ii) saturation mechanism of guide field tearing in three-dimensions.
DE: 2740 Magnetospheric configuration and dynamics
DE: 2756 Planetary magnetospheres (5443, 5737, 6030)
DE: 7835 Magnetic reconnection
DE: 7843 Numerical simulation studies
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting