  Statistical properties of the interplanetary magnetic field fluctuations can
provide an important insight into the solar wind turbulent cascade. Recently,
analysis of the Probability Density Functions (PDF) of the velocity and
magnetic field fluctuations has shown that these exhibit non-Gaussian
properties on small time scales while large scale features appear to be
uncorrelated. Here we apply the finite size scaling technique to explore the
scaling of the magnetic field energy density fluctuations as seen by WIND. We
find a single scaling sufficient to collapse the curves over the entire
investigated range. The rescaled PDF follow a non Gaussian distribution with
asymptotic behavior well described by the Gamma distribution arising from a
finite range Levy walk. Such mono scaling suggests that a Fokker-Planck
approach can be applied to study the PDF dynamics. These results strongly
suggest the existence of a common, nonlinear process onthe time scale up to ~26
hours.
