SPRG Seminars
November 06, 2012:
"MHD turbulence in the Solar Wind: the energy cascade"
L. Sorriso-Valvo, SSL/UC Berkeley & IPCF/CNR, Cosenza, Italy
Low frequency fluctuations of solar wind fields are commonly investigated in the framework of fully developed magnetohydrodynamic turbulence. Despite the wide use of classic turbulence tools to understand the plasma dynamics, the existence of a MHD turbulent energy cascade has only been convincingly supported recently. While several indications of the presence of an intermittent cascade have been provided by using spectra, structure functions and PDFs, the actual evidence has been only achieved through the study of the scaling law of the fluctuations third order moment. The latest results and their implications are discussed here. Further indications about the multifractal nature of the cascade are also given. Finally, the formal characterization of the structures generated along the cascade is performed by extracting the proper modes of the time series, and compared with wavelet analysis.