Low-energy ion pitch-angle distribution in the outer magnetosphere: Ion zipper distributions

Ion pitch-angle distributions, measured in a near synchronous orbit, are predominantly field-aligned at low energies and predominantly peaked perpendicular to the magnetic field at higher energies. The transition from field-aligned fluxes to fluxes peaked predominantly perpendicular to the magnetic field occurs over a very narrow energy range. These ion distributions have been observed at all local times between 5.3 Re and 7.8 Re. This transition energy correlates between the ion transition energy and magnetic local time, L, Kp, or Dst.