The spatial structure of edge fluctuations in the Wendelstein 7-AS stellarator

Abstract

In the scrape-off layer and outermost edge of the Wendelstein 7-AS (W7-AS) stellarator, fluctuations of, mostly, ion saturation current Isat and floating potential Φfl have been measured with high poloidal, radial (both 2-3 mm) and temporal (0.5 µs) resolution. Parallel to the magnetic field, measurements with two probe tips on the same magnetic field line were performed.