On the Transition Between the Inner and Outer Plasma Sheet in the Earth's Magnetotail

Abstract

AbstractWe have statistically studied the average structure and properties of the plasma sheet in the Earth's magnetotail at radial distances between R∼8 and 32 RE on the basis of ion, electron, and magnetic field data from the Geotail spacecraft. Here we discuss the transition between the inner plasma sheet and the outer plasma sheet near the equatorial plane. The ion and electron number densities, pressures, and energy fluxes at high energies, as well as the magnetic field, generally decrease with increasing radial distance from the Earth. The characteristics of the flux changes are reflected in the radial pressure gradients. If the transition between the inner and outer plasma sheet is determined by the radial pressure gradient change, the ion and electron transitions are located, on average, at R∼11 to 13 RE and R∼11 to 17 RE, respectively, at the midnight meridian. It is possible that the ion transition is located earthward of the electron transition. Furthermore, we have estimated the electric field, the electric and diamagnetic drift velocities, and the κ parameter (the square root of the ratio of the minimum curvature radius of the magnetic field line to the maximum gyroradius), which differ between the ion inner and outer plasma sheet.