DISTRIBUTION OF IMPULSIVE ELECTRIC FIELD IN THE NEAR EARTH PLASMA SHEET DURING STORM AND NON-STORM TIME

The electric field data obtained by the Geotail satellite in the near earth plasma sheet were used to analyze the spatial distribution of the impulsive electric field during storm （Dst ＜ -25nT) and non-storm （Dst ＞ -25 nT） time. It is shown that the strong electric field （up to 5-8mV/m） associated with the earthward fast ion flow is produced in the region earthward of -16 Re. The electric field during the storm time is stronger and occurs in the region closer to the Earth. The stronger electric field that is located closer to the Earth is in association with the thinner plasma sheet and the closer distance of the plasma sheet inner edge to the Earth. It is inferred that the substorm injection during the storm time is more efficient to inject energetic particles into the ring current.