Dynamics of the plasma sheet in the near-Earth magnetotail by the impact of an interplanetary shock

The impact of an interplanetary shock significantly disturbs the Earth's magnetosphere. Although the disturbances in the magnetotail induced by such an impact have extensively been investigated in previous studies, they are not still fully understood. In this study, we examined the disturbances produced in the central plasma sheet observed by the Cluster spacecraft. After the sudden impulse (SI) on the ground, significant compression of the magnetotail was observed. Initially, the dominant direction of the compression was the dawn-dusk direction, but later it changed to the north-south direction. Ions and electrons in the plasma sheet were significantly energized in the energy range from similar to 5 to similar to 100 keV. The energization was more effective on electrons than ions, and the energy dependence of the energization suggests that this process is non-adiabatic. We suggest that these particles can serve as the seed population of relativistic particles in the radiation belts.