HR: 15:25h
AN: SM23D-08    [Abstracts]
TI: Oblique Propagation, Wave-Particle Interaction and Particle Distribution Functions in the Quasi-Perpendicular Bow Shock.
AU: * Osmane, A
EM: adnaneo@gmail.com
AF: University of New-Brunswick, 8 Bailey drive, Fredericton, NB E3B 5A3, Canada
AU: Hamza, A M
EM: ahmaza@unb.ca
AF: University of New-Brunswick, 8 Bailey drive, Fredericton, NB E3B 5A3, Canada
AU: Meziane, K
EM: karim@unb.ca
AF: University of New-Brunswick, 8 Bailey drive, Fredericton, NB E3B 5A3, Canada
AB: Recent results from the Cluster mission have stimulated theoretical investigations and simulations to explain ion distribution functions observed in the quasi-perp bow shock. [Meziane et al., 2001] High-time resolution observations have revealed distributions of gyrating ions that are gyrophase-bunched. When not produced at the shock, such distributions are believed to be resulting from interactions between field-aligned beams and low frequency beam-driven waves (ω <Ømega) [Hamza et al., 2005] The Conventional models used to account for such distributions assume that the waves are purely transverse, and that they propagate parallel to the ambient magnetic field. However observations indicate that these waves are propagating obliquely (θ <e; 30 ° ) with respect to the ambient magnetic field [Meziane et al., 2001]. A theoretical investigation of the non-relativistic wave-particle interaction in a background magnetic field with the electromagnetic wave propagating obliquely has been addressed previously, resulting in a dynamical system describing the wave interaction with a single ion in the absence of dissipation mechanisms. [Hamza et al., 2005] This dynamical system can be numerically integrated to construct the ion distribution functions by seeding the particles with different initial conditions. We compute the particle orbits and simulate the time evolution of the distribution functions based on Liouville's theorem of phase space density conservation. This exercise can then provide insights on the particle dynamics away from the shock. Meziane, K., C. Mazelle, R.P. Lin, D. LeQueau, D.E. Larson, G.K. Parks, R.P. Lepping (2001), Three dimensional observations of gyrating ions distributions far upstream from the Earth's bow shock and their association with low-frequency waves, J. Geophys. Res. 106, 5731 Hamza, A. M., K. Meziane, and C. Mazelle (2006), Oblique propagation and nonlinear wave particle processes, J. Geophys. Res., 111, A04104
DE: 2720 Energetic particles: trapped
DE: 7867 Wave/particle interactions (2483, 6984)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting