HR: 0830h
AN: SH31A-1079    [PDF]
TI: Linear Theory of Drift Tearing Modes at the Magnetopause
AU: * Daughton, W S
EM: daughton@lanl.gov
AF: LANL, MS B259, Los Alamos, NM 87545
AU: Karimabadi, H
EM: homa@san.rr.com
AF: Dept of ECE, UCSD, 9500 Gilman Drive, La Jolla, CA 92093-0407
AB: Although the tearing instability has been the subject of extensive research, the approximations typically employed are less accurate for current sheets with thickness comparable to a thermal ion gyroradius. In this work, the linear Vlasov stability of a Harris sheet with an arbitrary guide field is calculated using a formally exact approach in which the orbit integrals are computed numerically$^1$. Both electromagnetic and electrostatic contributions to the field perturbation are included and the eigenvalue problem for the resulting system of integro-differential equations is solved using a finite element representation of the eigenfunction. In addition, the calculation includes a finite wavevector in the direction of the current to examine the linear properties of the obliquely propagating drift tearing modes. The growth rate and mode structure are computed for a range of interesting parameters and the results are compared with previous linear calculations. Significant differences are found between these new linear results and previous theoretical treatments. For example the resonant ion contribution, which has been neglected in previous calculations, is found to significantly modify the linear properties of the mode in certain regimes. Given that the linear growth rate is critical in the debate over the location of reconnection at the magnetopause, these new findings point to the need to revisit previous studies of the tearing mode at the magnetopause.\\ \noindent $^1$ W. Daughton, {\em Physics of Plasmas} {\bf 10}, 3103 (2003)
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 7835 Magnetic reconnection
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting