MHD-kinetic transition in imbalanced Alfvénic turbulence
- Solar-Terrestrial Centre of Excellence, BIRA-IASB, Ringlaan-3-Avenue Circulaire, B-1180 Brussels (Belgium)
Alfvénic turbulence in space is usually imbalanced: amplitudes of waves propagating parallel and anti-parallel to the mean magnetic field B{sub 0} are unequal. It is commonly accepted that the turbulence is driven by (counter-)collisions between these counter-propagating wave fractions. Contrary to this, we found a new ion-scale dynamical range of the turbulence established by (co-)collisions among waves co-propagating in the same direction along B{sub 0}. Co-collisions become stronger than counter-collisions and produce steep non-universal spectra above certain wavenumbers dependent on the imbalance. Spectral indexes of the strong turbulence vary around ≳−3, such that steeper spectra follow larger imbalances. Intermittency steepens the −3 spectra further, up to −3.7. Our theoretical predictions are compatible with steep variable spectra observed in the solar wind at ion kinetic scales, but further verifications are needed by correlating observed spectra with measured imbalances.
- OSTI ID:
- 22868438
- Journal Information:
- Astrophysical Journal Letters, Vol. 832, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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