A PRELIMINARY ASSESSMENT OF ENERGETIC ION SPECIES IN FLUX ROPES PLASMOIDS IN THE DISTANT TAIL

Measurements of the Energetic Particles and Ion Composition (EPIC) ins trument on the Geotail satellite are used to investigate at high-time resolution the relative intensity enhancements of different ion specie s at energies similar to 10 keV-3 MeV during encounters of magnetic fi eld structures attributed to flux ropes or plasmoids in the distant ta il. An examination of six events reveals the new result that the compo sition varies considerably within the interval of the encounter of eac h structure as well as among different encounters. There is no consist ent trend for enhancement nor reduction of energetic ions from the ion ospheric source relative to that from the solar wind source during int ervals of flux ropes or plasmoids. A possible interpretation is that t hese plasma structures are connected to a particle source or sources a ctively modifying their compositional content while they are being eje cted downstream beyond similar to 100 R(E).