ESA Science & Technology - Spectra of turbulence cascade in the solar wind

First observed spectra of turbulence cascade in the solar wind from large scales (105 km) down to small scales (~3 km) as measured by the Cluster spacecraft.

The magnetic (red) and electric (black) field spectra show a remarkable agreement with the predictions of the gyro-kinetic theory (dashed lines; Howes et al. [2008]).

This plot proves that the energy continues cascading below the proton scale down to the electron scale where it is converted to heat (via electron Landau resonance) causing the steepening of the Bz spectrum to ~f-4 (strong steepening as a function of frequency generally means that increasing amounts of energy are taken rapidly away from the waves and transferred to particles as the frequency increases).