UPGOING ION-BEAMS .2. FLUID ANALYSIS AND MAGNETOSPHERE-IONOSPHERE COUPLING

Measurements made on the S3-3 satellite within upgoing ion beams are used to determine what role the beam regions play in ionosphere-magnetosphere coupling and auroral particle accelerations. Numerical integrations over the measured electon and ion distribution functions provide estimates of the contributions of these energetic particles to bulk properties of the auroral plasma. It is found that energetic ions carry most of the parallel momentum flux and that energetic electrons carry most of the energy flux and field-aligned current within ion beam regions. It is concluded that these energetic electrons carry upward field-aligned current all the way from the dense ionosphere to the distant magnetotail. The net current density carried by energetic electrons is associated with non-Maxwellian anisotropies (e. g. , loss cones) in the electron distribution functions. These electrons are not well approximated by a drifting Maxwellian distribution. Microscopic stability analysis shows that the observed EHC waves can be driven by an ion beam. The analysis suggests that there probably are very few cold electrons near the satellite when ion beams and EHC waves are detected. It also is suggested that the cold ion density may be maintained at a very low level within ion beams, although at larger density than that of the cold electrons. Finally, momentum fluxes are used to investigate forces exerted by the acceleration process and the way these forces are transmitted from the ionosphere to the magnetosphere.