Energetic oxygen ions stream up to magnetosphere

It has been generally believed that essentially all of the hot (0.1 to 50 keV) plasma ions and most of the more energetic Van Allen radiation belt ions contained within the Earth’s magnetic field (the magnetosphere) originated on the Sun and were protons and a few percent helium ions. Now it has been discovered from satellite measurements that energetic (0.5–16 keV) oxygen ions that originate in the Earth’s cold (eV) ionosphere are a major component of the hot plasma trapped in wide regions of the radiation belts during geomagnetic storms. These new findings, along with observations with the same instrument of energetic (keV) oxygen ions and protons streaming upward from the ionosphere into the magnetosphere, have stimulated a major reassessment of the physical processes responsible for the injection, acceleration, transport, and loss of the hot magnetospheric plasma.

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