HR: 0800h
AN: SM31B-0456    [Abstracts]
TI: Energetic Particles Observed by ISEE-1 and ISEE-2 in a Cusp Diamagnetic Cavity on September 29, 1978
AU: * Walsh, B M
EM: bwalsh@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: Lender, N M
EM: nlender@bu.edu
AF: Center for Space Physics, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, United States
AU: Chen, J
EM: jschen@bu.edu
AF: Center for Space Physics, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, United States
AU: Whitaker, K E
EM: katherine.whitaker@yale.edu
AF: Center for Space Physics, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, United States
AU: Whitaker, K E
EM: katherine.whitaker@yale.edu
AF: Department of Astronomy, Yale University, 260 Whitney Avenue, New Haven, CT 06520, United States
AB: Observations by the ISEE-1 and ISEE-2 spacecraft on September 29, 1978 show large CEP (Cusp Energetic Particle) fluxes while passing through the dayside magnetospheric cusp in near coincident orbits. The event was observed around 11 MLT between roughly 12:30 and 13:00 UT by ISEE-1 and 12:00 and 13:00 UT by ISEE-2. During these periods, both electron and ion fluxes increased by more than two orders of magnitude. A boundary sounding technique was used to probe the location and orientation of a cusp boundary as the spacecraft approached. Inside this cusp cavity, pitch angle distributions of the electrons showed a strong peak at a pitch angle of 90°. During this period, the solar wind was ~710 km/s and the Dst was ~-200 nT, suggesting the occurrence of a strong geomagnetic storm. The ISEE-1 and ISEE-2 observations, however, show no time-energy dispersion of the CEPs, leading us to believe that these particles could not be the result of substorm processes in the magnetotail. Inside the cavity, the local magnetic field was depressed and extremely turbulent. These changes in the local magnetic field strength anticorrelate closely to variations of the electron flux. The observations of electron flux peaking at 90° and the close anticorrelation between strength of the local magnetic field and electron flux are unique and provide evidence of a potential local source for these energetic particles.
DE: 2700 MAGNETOSPHERIC PHYSICS (6939)
DE: 2706 Cusp
DE: 2716 Energetic particles: precipitating
DE: 2740 Magnetospheric configuration and dynamics
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting