Radial profiles of plasma turbulent fluctuations in the scrape-off layer of the Tore Supra tokamak

The measurements of ion saturation current fluctuations in the scrape-off layer of the Tore Supra tokamak are presented. As the radial distance from last closed flux surface increases more and more rare, but larger positive bursts become dominant in the signal and its probability density function becomes strongly asymmetric with pronounced positive tail. At the same time burst duration and inter-burst time increase dramatically. We explain this phenomenon by radial propagation and dynamics of the ensemble of different size large scale coherent structures.