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Article Dans Une Revue The Astrophysical Journal Année : 2017

Energy Cascade Rate in Compressible Fast and Slow Solar Wind Turbulence

Lina Hadid
Fouad Sahraoui
Sébastien Galtier

Résumé

Estimation of the energy cascade rate in the inertial range of solar wind turbulence has been done so far mostly within incompressible magnetohydrodynamics (MHD) theory. Here, we go beyond that approximation to include plasma compressibility using a reduced form of a recently derived exact law for compressible, isothermal MHD turbulence. Using in situ data from the THEMIS/ARTEMIS spacecraft in the fast and slow solar wind, we investigate in detail the role of the compressible fluctuations in modifying the energy cascade rate with respect to the prediction of the incompressible MHD model. In particular, we found that the energy cascade rate (1) is amplified particularly in the slow solar wind; (2) exhibits weaker fluctuations in spatial scales, which leads to a broader inertial range than the previous reported ones; (3) has a power-law scaling with the turbulent Mach number; (4) has a lower level of spatial anisotropy. Other features of solar wind turbulence are discussed along with their comparison with previous studies that used incompressible or heuristic (nonexact) compressible MHD models.

Dates et versions

hal-01895704 , version 1 (15-10-2018)

Identifiants

Citer

Lina Hadid, Fouad Sahraoui, Sébastien Galtier. Energy Cascade Rate in Compressible Fast and Slow Solar Wind Turbulence. The Astrophysical Journal, 2017, 838 (1), pp.9. ⟨10.3847/1538-4357/aa603f⟩. ⟨hal-01895704⟩
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