Identification of intermittent transport in the scrape-off layer of MAST through high speed imaging

Abstract

Using footage from high speed movies taken of the boundary plasma in the Mega Amp Spherical Tokamak (MAST) general properties of filaments are inferred through statistical moments. Filaments are observed up to and beyond the ψN=1.5 flux surface which, in single null configurations, lies well beyond the secondary separatrix and leads to filaments observed > 30cm from the top of the plasma. In the divertor filaments are observed to connect through to the target, however a quiescent region is observed close to the X-point where no coherent filaments are identified. This region coincides with a sharp rise in the integrated magnetic shear which may change the nature of the filament cross-section.