THIN CURRENT SHEETS IN THE DEEP GEOMAGNETIC TAIL

The ISEE-3 magnetic field and plasma electron data from Jan - March 19 83 have been searched to study thin current sheets in the deep tail re gion. 33 events were selected where the spacecraft crossed through the current sheet from lobe to lobe within 15 minutes. The average thickn ess of the observed current sheets was 2.45R(E), and in 24 cases the c urrent sheet was thinner than 3.OR(E); 6 very thin current sheets (thi ckness lambda < 0.5R(E)) were found. The electron data show that the v ery thin current sheets are associated with considerable temperature a nisotropy. On average, the electron gradient current was approximately 17% of the total current, whereas the current arising from the electr on temperature anisotropy varied between 8 - 45% of the total current determined from the lobe field magnitude.