HR: 0800h
AN: SM11A-1167    [Abstracts]
TI: Observations of ion velocity space holes associated with magnetic field fluctuations in the plasma sheet
AU: * Lee, E
EM: eslee@ssl.berkeley.edu
AF: Space Sciences Lab., UC Berkeley, 7 Gauss way, Berkeley, CA 94720 United States
AU: Parks, G K
EM: parks@ssl.berkeley.edu
AF: Space Sciences Lab., UC Berkeley, 7 Gauss way, Berkeley, CA 94720 United States
AU: Wilber, M
EM: wilber@ssl.berkeley.edu
AF: Space Sciences Lab., UC Berkeley, 7 Gauss way, Berkeley, CA 94720 United States
AU: Fillingim, M
EM: matt@ssl.berkeley.edu
AF: Space Sciences Lab., UC Berkeley, 7 Gauss way, Berkeley, CA 94720 United States
AU: Lin, N
EM: nlin@ssl.berkeley.edu
AF: Space Sciences Lab., UC Berkeley, 7 Gauss way, Berkeley, CA 94720 United States
AU: McFadden, J
EM: mcfadden@ssl.berkeley.edu
AF: Space Sciences Lab., UC Berkeley, 7 Gauss way, Berkeley, CA 94720 United States
AU: Dandouras, I
EM: iannis.dandouras@cesr.fr
AF: CESR, 9 ave de Colonel Roche, Toulouse, 31028 France
AU: Reme, H
EM: reme@cesr.fr
AF: CESR, 9 ave de Colonel Roche, Toulouse, 31028 France
AU: Sauvaud, J
EM: sauvaud@cesr.fr
AF: CESR, 9 ave de Colonel Roche, Toulouse, 31028 France
AU: Bosqued, J
EM: bosqued
AF: CESR, 9 ave de Colonel Roche, Toulouse, 31028 France
AU: Lucek, E
EM: e.lucek@imperial.ac.uk
AF: Blackett Lab., Imperial College, Prince Consort Road, London, SW7 2BZ United Kingdom
AU: Kistler, L
EM: lynn.kistler@unh.edu
AF: Univ. of New Hampshire, Morse Hall, Durham, NH 03824 United States
AU: Moebius, E
EM: eberhard.moebius@unh.edu
AF: Univ. of New Hampshire, Morse Hall, Durham, NH 03824 United States
AU: McCarthy, M
EM: mccarthy@u.washington.edu
AF: Univ. of Washington, Box 351310, Seattle, WA 98195 United States
AU: Klecker, B
EM: berndt.klecker@mpe.mpg.de
AF: Max-Planck Institut fuer Extraterrestriche, Postfach 1312, Garching, 85741 Germany
AU: Korth, A
EM: korthsprotte@mpae.gwdg.de
AF: PhysikMax-Planck Institute fuer Aeronomie, Max-Planck-Str 2, Katlenburg-Lindau, 37191 Germany
AU: Bavassano-Catanneo, M -
EM: bice@ifsi.rm.cnr.it
AF: IFSI CNR, Area di Ricerca di Toz Vergata, Rome, 00133 Italy
AU: Lundin, R
EM: rickard.lundin@irf.se
AF: Swedish Institute of Space Physics, POB 812, Kiruna, S-98128 Sweden
AB: During geomagnetically active periods, magnetic field fluctuations are frequently observed. We present Cluster ion observations obtained in the near-Earth magnetotail from 15 to 20 Re. When field fluctuations are prominent, ion distributions become irregular. In particular, holes appear in ion velocity space distributions in the tailward direction. On the other hand, ions moving in the Earthward direction are accelerated and form beam-like distributions. The holes in velocity space are gyrophase dependent and suggest a sink of particles nearby the spacecraft. The directions of ion holes and beam-like distributions are quite steady even though magnetic field direction is changing. This results in high anisotropy in V$_\perp$, which yields large velocity moments perpendicular to the magnetic field. The presence of large $\partial$B/B suggests that a temporal mechanism (for example, scattering by waves) plays a role in the formation of the gyrophase-dependent holes and beam-like distributions. Possible mechamisms responsible for these observations will be investigated.
DE: 7827 Kinetic and MHD theory
DE: 2740 Magnetospheric configuration and dynamics
DE: 2744 Magnetotail
DE: 2748 Magnetotail boundary layers
DE: 2764 Plasma sheet
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting