HR: 14:40h
AN: SM43A-03 INVITED     [Abstracts]
TI: In-situ observations of the cross shock electric field at Earth's bow shock and implications for foreshock dynamics
AU: * Eastwood, J P
EM: eastwood@ssl.berkeley.edu
AF: UC Berkeley, Space Sciences Laboratory, 7 Gauss Way, UC Berkeley, Berkeley, CA 94720, United States
AU: Bale, S D
EM: bale@ssl.berkeley.edu
AF: UC Berkeley, Dept. of Physics, UC Berkeley, Berkeley, CA 94720, United States
AU: Mozer, F S
EM: mozer@ssl.berkeley.edu
AF: UC Berkeley, Space Sciences Laboratory, 7 Gauss Way, UC Berkeley, Berkeley, CA 94720, United States
AU: Hull, A J
EM: ahull@ssl.berkeley.edu
AF: UC Berkeley, Space Sciences Laboratory, 7 Gauss Way, UC Berkeley, Berkeley, CA 94720, United States
AB: Of all the ways in which a magnetized collisionless plasma shock differs from its neutral fluid counterpart, one of the most striking is the fact that at a collisionless shock, particles are observed to stream from the shock back into the upstream region. The combination of the backstreaming particles together with the upstream core plasma distribution is subject to a number of instabilities that lead to the generation of waves and subsequent wave-particle interactions, all forming an integral part of the shock. A key part of this process is the formation of the reflected ion population, which strongly depends on the electric field structure of the shock. The Cluster mission is a constellation of four identical spacecraft in polar orbit around the Earth and is designed to resolve spatial and temporal variations in space plasmas, in particular at the Earth's bow shock. We have used its multi-spacecraft capability to determine the structure of the current inside the shock, and investigate the out of plane magnetic field. New observations of the electric field are used to investigate the structure of the shock on ion scales; in particular the contribution of the Hall term in the generalized Ohm's law. These observations have implications for the dynamics of ion reflection and beam formation, which are discussed.
DE: 4455 Nonlinear waves, shock waves, solitons (0689, 2487, 3280, 3285, 4275, 6934, 7851, 7852)
DE: 7829 Kinetic waves and instabilities
DE: 7846 Plasma energization
DE: 7851 Shock waves (4455)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly