Generation of macroscopic magnetic‐field‐aligned electric fields by the convection surge ion acceleration mechanism

The “convection surge” computer model presented previously (concerning the dramatic, nonadiabatic, magnetic‐field‐aligned energization of ions near the Earth's geosynchronous orbit in the presence of strong, transient, magnetic‐field‐perpendicular inductive electric fields) has been extended to include the self‐consistent generation of magnetic‐field‐aligned electric fields. The field‐aligned electric potential is obtained by imposing the quasi‐neutrality condition using approximated electron distribution forms. The ions are forced to respond self‐consistently to this potential. It is found that field‐aligned potential drops up to 1 to 10 kV can be generated depending on electron temperatures and on the mass species of the ions. During transient periods of the process, these large potential drops can be confined to a few degrees of magnetic latitude at positions close to the magnetic equator. Anomalous, sometimes dramatic, additional magnetic‐field‐aligned ion acceleration also occurs in part as a result of a quasi‐resonance between the parallel velocities of some ions and the propagating electric potential fronts. It is speculated that the convection surge mechanism could be a key player in the transient, field‐aligned electromagnetic processes observed to operate within the middle (e.g., geosynchronous) magnetosphere.