Generation of blobs and holes in the edge of the ASDEX Upgrade tokamak

The intermittent character of turbulent transport is investigated with Langmuir probes in the scrape-off layer and across the separatrix of ASDEX Upgrade Ohmic discharges. Radial profiles of plasma parameters are in reasonable agreement with results from other diagnostics. The probability density functions of ion-saturation current fluctuations exhibit a parabolic relation between skewness and kurtosis. Intermittent blobs and holes are observed outside and inside the nominal separatrix, respectively. They seem to be born at the edge of the plasma and are not the foothills of avalanches launched in the plasma core. A strong shear flow was observed 1 cm radially outside the location where blobs and holes seem to be generated.