THIN CURRENT SHEETS IN THE DEEP GEOMAGNETIC TAIL

The ISEE-3 magnetic field and plasma electron data from Jan - March 1983 have been searched to study thin current sheets in the deep tail region. 33 events were selected where the spacecraft crossed through the current sheet from lobe to lobe within 15 minutes. The average thickness of the observed current sheets was 2.45R(E), and in 24 cases the current sheet was thinner than 3.OR(E); 6 very thin current sheets (thickness lambda < 0.5R(E)) were found. The electron data show that the very thin current sheets are associated with considerable temperature anisotropy. On average, the electron gradient current was approximately 17% of the total current, whereas the current arising from the electron temperature anisotropy varied between 8 - 45% of the total current determined from the lobe field magnitude.