The second pair in the INTERBALL quartet: Some main results Original Research Article

The INTERBALL-2 satellite (AURORAL PROBE) was launched on August 29, 1996, about a year after the INTERBALL-1 and MAGION-4 pair already worked on a higher orbit. It performed comprehensive measurements of magnetospheric plasmas and fields mainly at altitudes 2 – 3 RE during more than two years. Some of the main findings from these measurements are briefly reviewed, in particular: 1. Discovery of long-duration high-energy electron dispersion events above the polar edge of the post-midnight auroral oval. 2. Discovery of high-energy (> 20 keV, i.e. super-auroral energy) upward moving field-aligned electron beams accompanied by bi-directional electrons ∼ 1 keV, also in these auroral regions. 3. Mass-resolved velocity-dispersed ion structures (VDIS) extended down to superthermal energies injected in the plasma flux tubes at the auroral oval polar border in a wide range of local times. 4. Mid-altitude ion distribution functions in the cusp showing a combination of downward moving, and mirror reflected, magnetosheath ions, with upward moving thermal and superthermal H+, He+, and O+ ions of the “cleft ion fountain” starting from eV energy range. 5. Thermal and superthermal plasma outflows of the classic polar wind type (only H+ and He+, no O+) as contrasted to conditions when additional acceleration mechanisms are operating which accelerate thermal heavy ions also (O+, etc.).