HR: 1340h
AN: SM33B-0458    [Abstracts]
TI: Interchange Instability in the Plasma Sheet
AU: * Xing, X
EM: xyxing@rice.edu
AF: Department of Physics and Astronomy, Rice University, MS108 P. O. Box 1892, Houston, TX 77251 United States
AU: Wolf, R A
EM: rawolf@rice.edu
AF: Department of Physics and Astronomy, Rice University, MS108 P. O. Box 1892, Houston, TX 77251 United States
AB: We have combined two empirical numerical models to estimate PV ^5/3 in the plasma sheet, where P is the plasma sheet pressure and V=∫ ds/B is the flux tube volume containing one unit of magnetic flux. The Tsyganenko [1996] magnetic field model is used to calculate the flux tube volume, and the Tsyganenko-Mukai [2003] plasma sheet statistical model is used to calculate the plasma sheet pressure. Contour plots of P,V and PV ^5/3 in the equatorial plane are presented for various solar wind conditions. These empirical models suggest that, although both PV ^5/3 and V generally increase tailward, their gradients are generally not parallel or antiparallel to each other. Most discussions of interchange instability assume that the gradients of PV ^5/3 and V either parallel or antiparallel. However, our empirical-model results suggest that the real plasma sheet does not satisfy these conditions. Furthermore, the Vasyliunas equation implies that the Birkland current is proportional to the cross product of ∇ PV ^5/3 and ∇ V. The fact that region 1 and region 2 Birkland current flow between plasma sheet and ionosphere confirms that these two gradients are not generally parallel. We present first results of some simple analytical calculations designed to investigate the criterion for interchange instability in quasi-static plasma where ∇ PV ^5/3 and ∇ V are at an arbitrary angle.
DE: 2740 Magnetospheric configuration and dynamics
DE: 2764 Plasma sheet
DE: 2772 Plasma waves and instabilities (2471)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005