HR: 1340h
AN: SM23A-0498    [Abstracts]
TI: Generation of Filaments by Beam-Plasma Interaction
AU: * Wang, X
EM: xywang@physics.auburn.edu
AF: Auburn University, Physics Department, Auburn, AL 36849 United States
AU: Chen, L
EM: liuchen@uci.edu
AF: University of California at Irvine, Department of physics and Astronomy, Irvine, CA 92697 United States
AU: Lin, Y
EM: ylin@physics.auburn.edu
AF: Auburn University, Physics Department, Auburn, AL 36849 United States
AB: Filaments have been observed near the bow shock and in other regions of Earth's magnetospheric plasmas. In this study, we carry out two dimensional hybrid simulations to investigate the structures and generation of filaments via interaction between the background plasma and an ion beam, whose velocity is parallel to the ambient magnetic field $B_0$. For the case with beam density $n_b=0.1$ and beam velocity $V_b=10V_A$, the simulation shows that right-hand nonresonant modes are dominant in the earlier linear stage, consistent with the linear theory prediction. In the nonlinear stage, the dynamics are, however, dominanted by two Alfven modes. While one Alfven wave mode propagates along $B_0$, the other is obliquely propagating. In the last stage of nonlinear wave evolution, filaments corresponding to field aligned structures of magnetic field $B$ and density $N$ are formed. The dominant filaments have anti-phase relation between $B$ and $N$, and nearly zero phase speed. Shear Alfven waves, meanwhile, remain coexisting with the filaments. The detailed mechanism for filament formation and nonlinear wave evolution will be presented.
DE: 7839 Nonlinear phenomena
DE: 7843 Numerical simulation studies
DE: 7867 Wave/particle interactions
DE: 7868 Wave/wave interactions
DE: 7871 Waves and instabilities
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting