HR: 1340h
AN: SM33C-0467    [Abstracts]
TI: CEPs are an Additional Source of Outer Radiation Belt Charged particles
AU: * Cheb, J
EM: jschen@bu.edu
AF: Center for Space Physics, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 United States
AU: Fritz, T A
EM: fritz@bu.edu
AF: Center for Space Physics, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 United States
AU: Sheldon, R B
EM: Rob.Sheldon@msfc.nasa.gov
AF: NASA/MSFC/NSSTC/XD12, 320 Sparkman, Huntsville, AL 35805 United States
AB: The cusp energetic particles (CEPs) can be energized locally by both resonant and stochastic acceleration mechanisms. The CEPs have been compared with the energetic ions in the outer radiation belt. The observations show that (1) the proton phase space densities in the outer radiation belt are organized by the magnetic moment and are independent of the solar wind conditions, (2) the phase space density of the belt He⁺⁺ and O⁺ ions, at a given magnetic moment, increased with increasing latitude and altitude, (3) the observed phase space densities of both the He⁺⁺ and O⁺ ion species in the cusp are significantly higher than those measured in the outer radiation belt at a given magnetic moment. The new fact (3) is very surprising because the radiation belt ions have much longer trapping time than the CEPs. Three different types of ion pitch angle distributions have been observed in the outer radiation belt at the same time. In the outer radiation belt, when the proton pitch angles showed a peak at 90° distribution (a stable trapping population), the He⁺⁺ and O⁺ showed an isotropic distribution and a butterfly distribution, respectively, which suggest new ion sources from both parallel and anti-parallel field directions. Such directions may be connected magnetically to the equatorward edges of the southern and the northern cusps. These observational facts suggest that the CEPs are a potentially additional source of the charged particles in the outer radiation belt.
DE: 2712 Electric fields (2411)
DE: 2720 Energetic particles: trapped
DE: 2724 Magnetopause and boundary layers
DE: 2731 Magnetosphere: outer
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005