Plasma sheet thickness and electric currents

Two years of Geotail data in the (-30 < x < -8, /y/ < 15) R-E region first were sorted into (x, y, ) boxes. Direct measurements of the average electron and ion current densities, symmetry assumptions, and the momentum equation were used to get three different estimates of the electric current in each box. The momentum equation method gave the most consistent results, while the other two methods provided complementary information about particle drifts. The average common drift of electrons and ions was found to be comparable to the average differential drift of ions with respect to elections. These two components of the ion drift velocity tended to cancel on the dawnside, resulting in currents that were primarily carried by electrons moving at the common drift speed. The two ion drifts added on the duskside where ions carried most of the cross-tail current. The particle and magnetic field measurements were used to estimate the z thickness of each beta box. A concentration of the long-term-averaged cross-tail current was seen near the neutral sheet. The region of nonadiabatic orbital motion had an average characteristic length scale of similar to0.4 R-E. The principal plasma sheet extended to similar to2.5 R-E from the neutral sheet at midnight and to similar to5 R-E in the flanks. The final result is a method to create models in (x, y, z) coordinates of the long-term-averaged values of any of the measured fluid parameters or fields. The isotropic portion of the pressure tenser was used as an example of one parameter that can be modeled. These pressure plots showed that the x component of the long-term-averaged magnetic field line tension force is important everywhere, that the z component is small everywhere, and that the y component is significant in the flanks.