The Energy Cascade in Solar Wind MHD Turbulence
Bavassano, B.; Bruno, R.; Carbone, V.; Sorriso-Valvo, L.; Marino, R.; Noullez, A.
Italy, France
Abstract
Direct evidence for the presence of an inertial energy cascade, the most characteristic signature of hydromagnetic turbulence (MHD), is observed in the solar wind by the Ulysses spacecraft. A linear relation is indeed observed for the scaling of mixed third order structure functions involving Elsässer variables. This experimental result, confirming the prescription stemming from a theorem for MHD turbulence, firmly establishes the turbulent character of low-frequency velocity and magnetic field fluctuations in the solar wind plasma.