Fractal dissipation of small-scale magnetic fluctuations in solar wind turbulence as seen by CLUSTER

Abstract

A robust multiscale analysis of high-frequency magnetic field measurements from the Cluster spacecraft is presented using complimentary measurements from the magnetometer and search-coil instruments; in a stationary interval of fast ambient solar wind. We show a surprising and novel result: that for time-scales smaller than the ion-gyro period the magnetic field fluctuations exhibit non-Gaussian monoscaling i.e. are globally scale invariant and can be characterized by a single scaling exponent and thus a single universal scaling function for the probability density. This presents new questions, as well as theoretical constraints, for determining how magnetic turbulent energy is dissipated in collisionless plasmas.