Where Does Fluid-like Turbulence Break Down in the Solar Wind?
Abstract
Power spectra of the magnetic field in solar wind display a Kolmogorov law f -5/3 at intermediate range of frequencies f, say within the inertial range. Two spectral breaks are also observed: one separating the inertial range from an f -1 spectrum at lower frequencies, and another one between the inertial range and an f -7/3 spectrum at higher frequencies. The breaking of fluid-like turbulence at high frequencies has been attributed to either the occurrence of kinetic Alfvén wave fluctuations above the ion-cyclotron frequency or to whistler turbulence above the frequency corresponding to the proton gyroradius. Using solar wind data, we show that the observed high-frequency spectral break seems to be independent of the distance from the Sun, and then of both the ion-cyclotron frequency and the proton gyroradius. We suppose that the observed high-frequency break could be either caused by a combination of different physical processes or associated with a remnant signature of coronal turbulence.
- Publication:
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The Astrophysical Journal
- Pub Date:
- December 2010
- DOI:
- 10.1088/2041-8205/725/1/L52
- Bibcode:
- 2010ApJ...725L..52P
- Keywords:
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- interplanetary medium;
- turbulence