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| Titel |
Turbulent spectra and spectral kinks in the transition range from MHD to kinetic Alfvén turbulence |
| VerfasserIn |
Y. Voitenko, J. Keyser |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 18, no. 5 ; Nr. 18, no. 5 (2011-09-13), S.587-597 |
| Datensatznummer |
250013966
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| Publikation (Nr.) |
 copernicus.org/npg-18-587-2011.pdf |
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| Zusammenfassung |
| A weakly dispersive range (WDR) of kinetic Alfvén turbulence is
identified and investigated for the first time in the context of
the MHD/kinetic turbulence transition. We find
perpendicular wavenumber spectra ∝ k⊥−3 and ∝
k⊥−4 formed in WDR by strong and weak turbulence of kinetic Alfvén waves
(KAWs), respectively. These steep WDR spectra connect shallower
spectra in the MHD and strongly dispersive KAW ranges, which results in
a specific double-kink (2-k) pattern often seen in observed turbulent
spectra. The first kink occurs where MHD turbulence transforms into weakly
dispersive KAW turbulence; the second one is between weakly and strongly
dispersive KAW ranges. Our analysis suggests that partial
turbulence dissipation due to amplitude-dependent non-adiabatic ion
heating may occur in the vicinity of the first spectral kink. The
threshold-like nature of this process results in a conditional selective
dissipation that affects only the largest over-threshold
amplitudes and that decreases the intermittency in the range below
the first spectral kink. Several recent counter-intuitive observational
findings can be explained by the coupling between such a selective
dissipation and the nonlinear interaction among weakly dispersive
KAWs. |
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