SOLAR WIND TURBULENT SPECTRUM AT PLASMA KINETIC SCALES

• Published in: The Astrophysical journal 2012-12, Vol.760 (2), p.1-6
• Main Authors: ALEXANDROVA, O, LACOMBE, C, MANCENEY, A, GRAPPIN, R, MAKSIMOVIC, M
• Format: Article
• Language: English
• Subjects: ASTRONOMY; ASTROPHYSICS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Earth, ocean, space; ENERGY SPECTRA; Exact sciences and technology; Fluctuation; FLUCTUATIONS; Fluid dynamics; IONS; LANDAU DAMPING; LARMOR RADIUS; MAGNETIC FIELDS; Physics; PLASMA; Plasma Physics; SOLAR ELECTRONS; SOLAR WIND; Spacecraft; Spectra; TURBULENCE
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637x/760/2/121

The description of the turbulent spectrum of magnetic fluctuations in the solar wind in the kinetic range of scales is not yet completely established. Here, we perform a statistical study of 100 spectra measured by the STAFF instrument on the Cluster mission, which allows us to resolve turbulent fluctuations from ion scales down to a fraction of electron scales, i.e., from ~10 super(2) km to ~300 m. We show that for k sub([perpendicular])[rho]e [isin] [0.03, 3] (which corresponds approximately to the frequency in the spacecraft frame f [isin] [3, 300] Hz), all the observed spectra can be described by a general law E(k sub([perpendicular])) [is proportional to] k super(-8/3) sub([perpendicular]) exp(-k sub([perpendicular])[rho]e), where k sub([perpendicular]) is the wavevector component normal to the background magnetic field and [rho]e the electron Larmor radius. This exponential tail found in the solar wind seems compatible with the Landau damping of magnetic fluctuations onto electrons.