The Properties of Ionospheric Singly Ionized Oxygen Ions as Observed in the Magnetotail Boundary Layer and Northern Plasma Lobe

摘要

The singly ionized oxygen ion beams flowing in the geomagnetic tail low latitude boundary layer and northern plasma lobe were investigated, using the ISEE-2 positive ion experiment. The data analysis shows that the ion velocity gradually increases from the center to the outer regions of the magnetotail, whereas the plasma density decreases the farther one moves away from the center. The temperature of the beaming ions is shown to be anisotropic with respect to the ambient magnetic field. The results clearly identify the E x B filter as the organizer of the flow of these ions after their initial acceleration in the topside ionosphere. Indications are that the acceleration mechanism is a combination of both electrostatic fields parallel to B and resonance with ion cyclotron waves.