HR: 1340h
AN: SM23A-0485    [Abstracts]
TI: Hybrid Simulations of Kinetically Excited Global Magnetospheric Alfv\'en Waves
AU: * Hu, S
EM: shuanghh@uci.edu
AF: Department of Physics and Astronomy, University of California, Irvine, CA 92697 United States
AU: Chen, L
EM: liuchen@uci.edu
AF: Department of Physics and Astronomy, University of California, Irvine, CA 92697 United States
AB: Shear Alfv\'en waves in the Earth's magnetosphere are investigated by a two-dimensional (2D) nonlinear gyrokinetic(GKE)-magnetohydrodynamic (MHD) hybrid simulation code based on the analytical formulation for two-component (core and energetic) plasmas [Frieman and Chen, 1982; Chen and Hasegawa, 1991]. While the core component, as the ideal MHD fluid, supports the Alfv\'en wave oscillations, the energetic component provides the kinetic instability drive via wave-particle resonances. Our preliminary studies have indicated that, given sufficiently strong energetic-particle drive, the excited Alfv\'en-ballooning modes can be radially trapped in the maximal kinetic drive region to form a 2D global unstable eigenmode; contrast to MHD predictions of no radial potential well structures. In the nonlinear state, our present focus is on the saturation mechanism of a coherent single-$m$ (the azimuthal wavenumber) unstable eigenmode. Specifically, we will explore nonlinear saturation via spatial detuning of wave-particle resonances due to the wave-induced radial excursions of energetic particles. Detailed 2D global stability features and saturation processes will be presented. Work supported by NSF and DOE Grants.
DE: 7827 Kinetic and MHD theory
DE: 7839 Nonlinear phenomena
DE: 7843 Numerical simulation studies
DE: 7867 Wave/particle interactions
DE: 2772 Plasma waves and instabilities
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting