HR: 09:45h
AN: SM51C-08    [Abstracts]
TI: Energetic Particle Behavior in the Magnetospheric Cusp Observed by ISEE-1
AU: Whitaker, K E
EM: whitaker.kate@gmail.com
AF: Boston University Center for Space Physics, 725 Commonwealth Ave., Boston, MA 02215, United States
AU: * Fritz, T A
EM: fritz@bu.edu
AF: Boston University Center for Space Physics, 725 Commonwealth Ave., Boston, MA 02215, United States
AU: Chen, J
EM: jschen@bu.edu
AF: Boston University Center for Space Physics, 725 Commonwealth Ave., Boston, MA 02215, United States
AU: Klida, M M
EM: mklida@bu.edu
AF: Boston University Center for Space Physics, 725 Commonwealth Ave., Boston, MA 02215, United States
AB: Observations on 30 October 1978 show the ISEE-1 spacecraft passing though the high altitude dayside northern magnetospheric cusp region from roughly 16:00 to 18:30 UT, during a slow solar wind period (~380 km/s). More than two orders of magnitude enhancements of the cusp energetic particle (CEP) fluxes were observed along with a depressed and turbulent local magnetic field. The observed variations of the pitch angle distributions (PAD) provide a unique opportunity to determine the structure of the cusp and the origin of the CEP fluxes. Through a boundary sounding technique, the location and orientation of the cusp poleward (or backside) boundary was observed for almost 10 minutes during which time it appeared initially to be stationary in the GSM/GSE X-direction and then move sunward about 0.12 Earth radii (RE). The orientation remained approximately perpendicular to the GSM/GSE X-axis until it was observed to rotate by 60 degrees in ~3 minutes before ISEE-1 was fully inside the cusp cavity. The cavity itself was filled with CEP fluxes displaying large anisotropies, indicative of their source being located below (Earthward) of the satellite location. The spacecraft entered from the backside of the cusp, then traveled ~4 RE through the cavity, and exited through the "top" of the cavity leaving a region of energetic ions below. The PADs demonstrate that the bow shock cannot be the main source of the observed CEPs. The CEP fluxes were measured at about 8.5 hours MLT when the IMF had both an 8-10 nT duskward and southward component.
DE: 2706 Cusp
DE: 2784 Solar wind/magnetosphere interactions
DE: 7807 Charged particle motion and acceleration
DE: 7845 Particle acceleration
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly