The hot ion composition energy and pitch angle characteristics above the auroral zone ionosphere

This chapter describes the ion fluxes in the auroral acceleration regions and identifies areas needing further ion composition studies. Topics considered include smaller scale ion features, upward flowing ion morphology, and selected special studies (evening sector beams, the dayside cusp region, the polar cap region, and downward flowing ion beams). The smaller scale spatial/temporal features are discussed on the basis of individual high latitude passes of the S3-3 spacecraft. No ion composition data below 500 eV are available from the S3-3 spacecraft although large fluxes of upward flowing ions are frequently observed in the energy range 90-400 eV. It is now established that intense upward flowing H234 and O234 ions with energies frequently extending to many keV are a continuous or nearly continuous feature of the high latitude auroral regions