HR: 1340h
AN: SH23A-1152 [Abstracts]
TI: Measurements of the phase speed of the solar wind turbulence at short wavelengths
AU: * Kilpua, S
EM: samik@ssl.berkeley.edu
AF: Space Science Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA
94720, United States
AU: Bale, S
EM: bale@ssl.berkeley.edu
AF: Space Science Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA
94720, United States
AU: Salem, C
EM: salem@ssl.berkeley.edu
AF: Space Science Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA
94720, United States
AU: Howes, G
EM: ghowes@astro.berkeley.edu
AF: Department of Astronomy, University of California, Berkeley, 601 Campbell Hall, Berkeley,
CA 94720, United States
AU: Quataert, E
EM: eliot@astro.berkeley.edu
AF: Department of Astronomy, University of California, Berkeley, 601 Campbell Hall, Berkeley,
CA 94720, United States
AU: Horbury, T
EM: .horbury@imperial.ac.uk
AF: The Blackett Laboratory, Imperial College, SW7 2BW, London, 1, United Kingdom
AB:
In this study we present results of electric and magnetic field fluctuation spectras in 14 intervals observed in the
ambient solar wind near 1 AU, using electric- and magnetic field and plasma measurements from Cluster and
ACE spacecrafts. The main focus is particularly on the energy transfer in the small scales (k ρ > 1), usually
referred as "dissipation range" in literature. It is however likely that it is a second inertial range caused by the
change in the dispersion relation as energy cascades to smaller wavelengths from Alfven waves in some
nonlinear process and heats the surrounding plasma.
In the inertial range electric and magnetic fluctuation spectras follow the classical fluid-like Kolmogorov behavior
as is previously observed. The fluid-like behavior breaks down near the ion thermal gyro-radius ( ρi) and
we observe an enhancement in the electric spectrum while the magnetic spectrum becomes steeper. Special
interest is paid to the in-situ measurements of the phase speed (vphi(k ρi)) of the turbulent plasma
and comparison of the approximated dispersion of the waves to the theoretical predictions, goal being to find out
the nature of the observed waves in the "dissipation range".
DE: 2149 MHD waves and turbulence (2752, 6050, 7836)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting