On the mechanism of plasma penetration and energetic electron escape across the dayside magnetopause

A statistical study of correlated observations of plasma, energetic (>40 keV) electrons and magnetic fields on HEOS-2 in the outer dayside magnetosphere and magnetosheath has been performed. We find that on the dayside magnetosphere the occurrence of plasma inside the magnetopause is anti-correlated with the appearance of energetic electrons in the magnetosheath. A mechanism is derived that attempts to explain how plasma may penetrate across the magnetopause into the magnetosphere and how energetic electrons may escape from the (pseudo) trapping region in the dayside magnetosphere into the magnetosheath. The mechanism is an E × B drift across the magnetopause. The drift is directed inward or outward depending on the direction of the electric field E at the magnetopause.