HR: 0830h
AN: SH21B-0121    [PDF]
TI: Wind Observations of Whistler Waves in the Solar Wind at 1 AU and Their Role on the Regulation of the Electron Heat Flux.
AU: * Salem, C S
EM: salem@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720-7450 United States
AU: Bale, S D
EM: bale@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720-7450 United States
AU: Hubert, D
EM: Daniel.Hubert@obspm.fr
AF: Observatoire de Paris, LESIA, 5 Place Jules Janssen, Meudon, 92195 France
AU: Kellogg, P J
EM: kellogg@waves.space.umn.edu
AF: School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55454 United States
AU: Lin, R P
EM: rlin@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720-7450 United States
AB: A weak but persistent level of electromagnetic noise with frequencies between the ion ($f_{ci} \sim 0.08$ Hz) and the electron ($f_{ce} \sim 150$ Hz) cyclotron frequencies has been observed in the ambient solar wind for more than 25 years. It is commonly believed that these fluctuations are due to whistler mode emissions, as their frequency range suggests. Yet, the origin and the properties of that ``background level" of waves and its role in the electron heat flux regulation in the solar wind at 1 AU is still poorly understood. We present observations from the WAVES experiment on WIND, near L1 during 50 days close to the last minimum of solar activity, using the FFT (Fast Fourier Transform) spectral receivers and the TDS (Time Domain Sampler) waveform analyzer. Magnetic spectra and waveforms observed between $f_{ci}$ and $f_{ce}$ are used to determine the properties of the waves. We analyze also the electron heat flux measured by the 3D-Plasma experiment, in relation to the background level of magnetic fluctuations. First, the nature of the wave mode is discussed: are they effectively whistler waves or, for example, kinetic Alfv\'en waves? Then, we show that these waves are likely to play a role in the regulation of the heat flux in the solar wind. According to recent theories, whistler waves reduce the intensity of the heat flux through wave-particle scattering associated with a heat flux instability. The possible source(s) of the waves are finally discussed : are they the result of a heat flux instability or the result of an existent nonlinear cascade of Alfv\'enic-like fluctuations?
DE: 2159 Plasma waves and turbulence
DE: 2164 Solar wind plasma
DE: 7859 Transport processes
DE: 7867 Wave/particle interactions
DE: 7871 Waves and instabilities
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting