期刊
Astrophysical Journal Letters
卷 832, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.3847/2041-8205/832/2/L20
关键词
solar wind; turbulence; waves
资金
- Belgian Science Policy Office (through Prodex/Cluster) [PEA 90316]
- Belgian Science Policy Office (through IAP Programme) [P7/08 CHARM]
Alfvenic turbulence in space is usually imbalanced: amplitudes of waves propagating parallel and anti-parallel to the mean magnetic field B-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-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 greater than or similar to -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.
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