The magnetic mirror force bends the orbits of electrons precipitating into the atmosphere. It has been suggested that relativistic electrons make much less ionization due to the force than if it did not exist, but the actual effectivity in the atmospheric electron density has not been revealed. We used conjugated observational data from the ELFIN satellite and the EISCAT Tromsø radar to find that the electron density decreased by about 40 % at 80 km altitude because of the force.

We have collected statistics of 81 fast plasma flow events in the magnetotail with clear MMS observations of kinetic Alfven waves (KAWs). We show that KAWs electric field magnitudes correlates with thermal/subthermal electron flux anisotropy: wider energy range of electron anisotropic population corresponds to higher KAWs’ electric field intensity. These results indicate on an important role of KAWs in production of thermal field-aligned electron population of the Earth’s magnetotail.

In the paper we study flapping wave structures, generated in the neutral plane of the Earth magnetotail. Investigated flapping is an important process of magnetosphere dynamics, connected with magnetic energy transformation and magnetic storm formation. Large separation of Cluster spacecraft allows us to estimate both local and global properties of flapping current sheets, the typical flapping times and propagation directions.