Measurement of the Electric Fluctuation Spectrum of Magnetohydrodynamic Turbulence
- Department of Physics and Space Sciences Laboratory, University of California, Berkeley, California 94720 (United States)
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States)
- Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom)
- CESR, 31400 Toulouse (France)
Magnetohydrodynamic (MHD) turbulence in the solar wind is observed to show the spectral behavior of classical Kolmogorov fluid turbulence over an inertial subrange and departures from this at short wavelengths, where energy should be dissipated. Here we present the first measurements of the electric field fluctuation spectrum over the inertial and dissipative wave number ranges in a {beta} > or approx. 1 plasma. The k{sup -5/3} inertial subrange is observed and agrees strikingly with the magnetic fluctuation spectrum; the wave phase speed in this regime is shown to be consistent with the Alfven speed. At smaller wavelengths k{rho}{sub i}{>=}1 the electric spectrum is enhanced and is consistent with the expected dispersion relation of short-wavelength kinetic Alfven waves. Kinetic Alfven waves damp on the solar wind ions and electrons and may act to isotropize them. This effect may explain the fluidlike nature of the solar wind.
- OSTI ID:
- 20696341
- Journal Information:
- Physical Review Letters, Vol. 94, Issue 21; Other Information: DOI: 10.1103/PhysRevLett.94.215002; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
Similar Records
A KINETIC ALFVEN WAVE CASCADE SUBJECT TO COLLISIONLESS DAMPING CANNOT REACH ELECTRON SCALES IN THE SOLAR WIND AT 1 AU
ASTROPHYSICAL GYROKINETICS: KINETIC AND FLUID TURBULENT CASCADES IN MAGNETIZED WEAKLY COLLISIONAL PLASMAS