PROPAGATION OF ELECTRON BURSTS IN THE LOW-LATITUDE MAGNETOSPHERE

The APEX project (Active Plasma Experiment) has been launched into a p olar orbit in December 1991 and consists of two satellites (IK-25 and MAGION-3), with a distance from approximate to 200 km to 10 000 km bet ween them. The paper deals with short intensive bursts of field-aligne d electrons observed during the APEX mission on board the MAGION-3 sat ellite. These events are predominantly located at the middle geomagnet ic latitudes in the day-side magnetosphere. The time-energy structure of these electron bursts is similar to the inverted-V one but the pitc h-angle width is less than 10 degrees. Electrons with an energy up to 700 keV are often observed during the events. We analyse the observed events, discuss the possible mechanisms of the particle spreading and the role of the activity of the main satellite as a possible source of these events.