HR: 1340h
AN: SM23A-0471    [Abstracts]
TI: Gyrokinetic Theory and Simualtion of Mirror Instability
AU: Qu, H
EM: hqu@uci.edu
AF: University of California, Department of Physics and Astronomy, Irvine, CA 92697 United States
AU: Chen, L
EM: liuchen@uci.edu
AF: University of California, Department of Physics and Astronomy, Irvine, CA 92697 United States
AU: * Lin, Z
EM: zhihongl@uci.edu
AF: University of California, Department of Physics and Astronomy, Irvine, CA 92697 United States
AB: Magnetic mirror instability plays an important role in low frequency magnetic turbulences in high-beta space plasmas, e.g., the Earth's magnetosheath, and also potentially in high-beta laboratory mirror or dipole plasmas with large fraction of trapped particles. A quasi-hydrodynamic analysis of kinetic mirror instability in non-Maxwellian plasmas recently found that the maximum growth rate increases with perpendicular wave number. Therefore, finite Larmor radius effects are important in determining the threshold and wavelength of kinetic mirror instability. In this study, we extend the kinetic theory for mirror instability to the short wavelength regime using the gyrokinetic theory and simulation. We have developed a general dispersion relation of the mirror mode with finite Larmor radius effects and arbitrary distribution functions, and have recovered the quasi-hydrodynamic results in the long wavelength limit. We find that the most unstable mode has a wavelength on the order of ion gyroradius. We also find that both the finite beta and coupling to the slow sound wave have stabilizing effects. Gyrokinetic particle simualtion will be used to benchmark these linear results and to identify nonlinear saturation mechanism.
DE: 2752 MHD waves and instabilities
DE: 2753 Numerical modeling
DE: 2772 Plasma waves and instabilities
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting