Dispersive Alfvén Wave Control of O⁺ Ion Outflow and Energy Densities in the Inner Magnetosphere

The relationship between dispersive Alfvén waves (DAWs), magnetospheric activity, and O⁺ ion outflow/energy density is examined using measurements from the Van Allen Probes. We show that correlated DAW activity and O⁺ outflow/energization is a characteristic feature of the inner magnetosphere during active conditions and during storms persists for several hours over large L-shell and azimuthal ranges of the plasma sheet. Though enhanced during substorm and storm active periods, these correlated features are most intense during geomagnetic storms. Comparisons show a linear relationship between DAW electric (and magnetic) field energy density and outflowing O⁺ energy. Statistical measurements from a large number of storms also reveal a linear relationship between DAW energy density and gross enhancements in energetic O⁺ energy densities. These observations support the notion that DAWs play an important role in the energization of O⁺ ions into and within the inner magnetosphere.