Field-Aligned Current in the Magnetotail Lobe

It is found that the bursts of energetic particle (electron: 75 keV≤E_e≤1300 keV,proton: 170 keV≤E_p<400 keV) and east-west magnetic field perturbations are sometimes observed simultaneously by ISEE-2 satellite in the magnetotail lobe far from the plasma sheet,which shows that there are field-aligned currents in the magnetotail lobe.The integral densities of the current sheet range from 3.3 to 21 mA/m.These values are comparable to previous observations of field-aligned current made by Frank et al.on the plasma sheet boun-dary of the magnetotail.The current sheets always appear in pairs and their integral densities have a good correlation with AE index.Differing from the other regions,eastwest mag-netic field perturbations are sometimes accompanied by south-north ones.The fact can be explained through moving linear current model or heterogeneous density model of current sheet.