Structure of plasma sheet in magnetotail: Double-peaked electric current sheet

The structure of the plasma sheet in the distant magnetotail observed by the Geotail satellite is examined. We found that the observed structure of the plasma sheet is often different from the standard Harris-type plasma sheet [Harris, 1962]. The observed structure can be expressed as a double-peaked current sheet which has a pair of localized electric currents away from the neutral sheet, i.e., a geometrically thick zero magnetic field region attached to the thin boundary layer with a large magnetic field gradient. This type of the plasma sheet is often observed in the distant magnetotail at radial distances of -50 > X(GSM)/R(E) > -125. We discuss a possible model to explain the formation of the double-peaked current sheet in terms of large-scale magnetic reconnection associated with slow shocks.