HR: 0800h
AN: SM41A-1107    [Abstracts]
TI: Drift-Shell Bifurcation
AU: Ozturk, M
EM: mkozturk@rice.edu
AF: Rice University, 6100 Main St. Physics and Astronomy Dept., Houston, TX 77081
AU: Wolf, R A
EM: rawolf@rice.edu
AF: Rice University, 6100 Main St. Physics and Astronomy Dept., Houston, TX 77081
AU: * Chan, A A
EM: aachan@rice.edu
AF: Rice University, 6100 Main St. Physics and Astronomy Dept., Houston, TX 77081
AB: Certain drift shells that pass sufficiently close to the dayside magnetosphere encounter a local maximum around the equatorial plane, and near local noon. As a result of that local maximum, the shell undergoes a bifurcation, with one branch in each hemisphere. Past the neighborhood of local noon, the branches meet again. The line where bifurcation occurs is a singular line, where the bounce period goes to infinity. As a result, the adiabaticity of the bounce motion breaks down and the post-bifurcation second invariant can be significantly different from the initial value. The first invariant is not broken. We provide simulations, and an analysis in terms of the "separatrix crossing" theory. The change in the second invariant is stronger with small mirror field, with small initial second invariant and with large kinetic energy. Also, bifurcation has the effect of creating "metastable shells", by keeping quasi-trapped particles inside the magnetosphere for a finite number of drifts.
DE: 7839 Nonlinear phenomena
DE: 2720 Energetic particles, trapped
DE: 2731 Magnetosphere--outer
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting