ON THE STRUCTURE OF THE MAGNETOTAIL CURRENT SHEET

Results from modeling ion distribution functions in a two-dimensional reduction of the Tsyganenko [1989] magnetic field model have enabled us to calculate the full ion pressure tensor inside the model magnetotail. A thin current sheet is formed in the distant tail and the pressure tensor within this sheet has significant off-diagonal terms. These terms resulting from quasiadiabatic ion trajectories create azimuthally asymmetric distribution functions which are capable of maintaining stress-balance. Outside the current sheet the off-diagonal terms disappear and moderate anisotropy builds up with P(perpendicular-to/P(parallel-to) approximately 0.8. Closer to the Earth rapid isotropization of the distribution occurs.