HR: 1340h
AN: SH53A-1249    [Abstracts]
TI: Ion Thermalization and Wave Excitation Downstream of Earth's Bow Shock: Cluster Data
AU: * Liu, Y C
EM: yongl@cisunix.unh.edu
AF: Physics Department, Univeristy of New Hampshire, Durham, NH 03824 United States
AU: Lee, M A
EM: marty.lee@unh.edu
AF: Physics Department, Univeristy of New Hampshire, Durham, NH 03824 United States
AU: Kucharek, H
EM: kucharek@atlas.sr.unh.edu
AF: Physics Department, Univeristy of New Hampshire, Durham, NH 03824 United States
AB: Thermalization of solar wind ions downstream of Earth's bow shock has been intensively investigated in the past with single spacecraft missions. However, temporal and spatial scales could not be determined. Cluster with its multi-spacecraft capabilities allows us to determine these quantities directly. We have used ion data from the ion composition instrument CIS and magnetic field data from the fluxgate magnetometer to investigate thermalization downstream of the quasi-perpendicular Earth's bow shock. We selected marginally supercritical shock crossings and determined thermalization time and length scales. The results show that part of the thermal energy, especially the portion of the thermal energy residing in motion perpendicular to the average magnetic field is converted into ion-cyclotron waves. The time scale for this process depends on the plasma environment downstream of the shock. To measure the distances of the spacecraft to the shock we use the method presented in Maksimovic et al. (2003). The resulting time scale shows good agreement with the prediction of quasilinear theory.
DE: 7829 Kinetic waves and instabilities
DE: 7851 Shock waves (4455)
DE: 7867 Wave/particle interactions (2483, 6984)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005