HR: 14:20h
AN: SM43A-02 INVITED     [Abstracts]
TI: Ion properties at Earth's foreshock, recent achievements
AU: * Mazelle, C
EM: christian.mazelle@cesr.fr
AF: CESR / UPS-CNRS, 9, Avenue du Colonel Roche, Toulouse, 31400, France
AU: Meziane, K
EM: karim@unb.ca
AF: Physics Department, University of New Brunswick, Fredericton, NB , Canada
AU: Wilber, M
EM: wilber@ssl.Berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA , United States
AU: Hamza, A
EM: ahamza@unb.ca
AF: Physics Department, University of New Brunswick, Fredericton, NB , Canada
AU: Lucek, E
EM: e.lucek@imperial.ac.uk
AF: Space & Atmospheric Physics Group, Imperial College London, London, United Kingdom
AU: Reme, H
EM: reme@cesr.fr
AF: CESR / UPS-CNRS, 9, Avenue du Colonel Roche, Toulouse, 31400, France
AB: Different types of backstreaming ion distributions have been reported in the ion foreshock: field-aligned beams (FABs), gyrating ions and diffuse ions distributions. Contrary to the first type, the two others are always associated with low frequency (ULF) waves. Multi-spacecraft observations by Cluster and the high quality 3-dimensional data obtained by Cluster/CIS has permitted to address specific quantitative questions that could not be resolved previously. Gyrating ions with well-defined pitch-angle and gyrophase organization around the local magnetic field have been frequently observed in association with large amplitude quasi-monochromatic waves. These waves reveal the existence of coherent wave-particle interaction which is an efficient process to dissipate the energy of the particles reflected at the collisionless bow shock. It has been shown recently from a Cluster data set that the gyrophase-bunched ion distributions are mainly produced by such a process from cyclotron-resonant FABs observed just at the edge of both the gyrating ions region and the boundary of ULF waves. New results have also been obtained on the FABs and gyrating ions exhibiting sometimes a high-energy tail likely produced by a local process at the shock which may be micro-turbulence. It has been found that the characteristics of both parallel and perpendicular particle distribution function profiles of field-aligned beams (FABs) are geometry-dependent. Other recent results deal with the properties of ion distributions associated with ULF waves with left-hand polarisation the existence of which has been definitively and unambiguously proven from the four-spacecraft analysis by Cluster. These recent achievements in the properties of ion distributions in the terrestrial ion foreshock will be discussed in the light of theoretical works and recent numerical simulations.
DE: 2154 Planetary bow shocks
DE: 2159 Plasma waves and turbulence
DE: 2784 Solar wind/magnetosphere interactions
DE: 7829 Kinetic waves and instabilities
DE: 7867 Wave/particle interactions (2483, 6984)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly