HR: 1340h
AN: NG23A-1186    [Abstracts]
TI: Properties of Chaotic Scattering in Current Sheets
AU: Matsuoka, H
EM: hmb@phy.ilstu.edu
AF: Illinois State University, Physics Department Campus Box 4560, Normal, IL 61790-4560 United States
AU: * Martin, R F
EM: rfm@phy.ilstu.edu
AF: Illinois State University, Physics Department Campus Box 4560, Normal, IL 61790-4560 United States
AU: Holland, D L
EM: holland@phy.ilstu.edu
AF: Illinois State University, Physics Department Campus Box 4560, Normal, IL 61790-4560 United States
AB: We investigate the Hamiltonian system of a charged particle in the modified Harris magnetic field model, relevant to the dynamics of current sheets in space plasmas. It is a localized scattering system as the particle stays in the current sheet or scattering region for a finite time interval before it escapes from the region. For some initial conditions, the motion of the particle has been found to be chaotic and the statistical properties of an ensemble of particle trajectories with a fixed energy have been shown to critically depend on the energy. At the resonant energies, the particle on a chaotic trajectory tends to stay in the current sheet region much longer than the particle on a chaotic trajectory with energy away from the resonant energies. Our numerical results show that the average Lyapunov exponent increases for higher resonant energies whereas away from the resonant energies it remains relatively small. In the talk, we will also show that the distribution of the Lyapunov exponents follows a universal functional form at both the resonant and the off-resonant energies.
DE: 7807 Charged particle motion and acceleration
DE: 2744 Magnetotail
DE: 3220 Nonlinear dynamics
SC: Nonlinear Geophysics [NG]
MN: 2004 AGU Fall Meeting