HR: 1340h
AN: SM23B-0435    [Abstracts]
TI: On linear theory of ion anisotropy instabilities in a current sheet
AU: * Quest, K B
EM: kquest@ucsd.edu
AF: UCSD Department of ECE, 9500 Gilman Drive, La Jolla, CA 92128-0407 United States
AU: Karimabadi, H
EM: homa@san.rr.com
AF: UCSD Department of ECE, 9500 Gilman Drive, La Jolla, CA 92128-0407 United States
AU: Daughton, W
EM: william-daughton@uiowa.edu
AF: The University of Iowa Department of Physics and Astronomy, 06 Van Allen Hall, Iowa City, IA 52242-1479 United States
AB: Our computer simulations and linear studies have shown that the presence of even a small electron anisotropy can strongly influence both the linear and nonlinear development of reconnection. In particular, it is well established that even a small thermal electron anisotropy parallel to the magnetic field can stabilize tearing mode growth, while a small perpendicular anisotropy can yield large enhancements. More recently we have shown that moderate ion anisotropies can also enhance the reconnection rate, particularly when the perpendicular temperature exceeds the parallel. Given that perpendicular ion anisotropies are routinely observed at the dayside magnetopause, it is important to further quantify this effect and establish its importance to reconnection. Observations show a correlation of ion anisotropy with plasma beta, so it would also be useful to determine which effect (anisotropy or plasma beta) is dominant in influencing the reconnection rate. Here we re-examine the linear stability of a bi-Maxwellian Harris equilibrium assuming thermal anisotropies in both electrons and ions. In particular, we derive approximate analytic expressions for bound tearing-like perturbations, and show that the predicted eigenfunctions and growth rates are in reasonable agreement with those of our linearized Vlasov solver. Limits of propagation parallel and perpendicular to the magnetic field will be considered, and the effects of plasma beta will be included.
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 2724 Magnetopause and boundary layers
DE: 2753 Numerical modeling
DE: 2772 Plasma waves and instabilities (2471)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005