Modelling Efforts on the Helical Near Field Divertor of the Dynamic Ergodic Divertor (DED) for TEXTOR‐94

Abstract

AbstractAs a first step for the modelling of the plasma‐wall interaction of the proposed Dynamic Ergodic Divertor (DED) of TEXTOR‐94, the topology of the magnetic field lines of the divertor is analysed. Despite the strong ergodization, the magnetic field lines intersecting the wall in one poloidal turn form continuous sets. These sets are visualised by a 2‐D imaging technique; the field lines of each set of starting values is traced one poloidal turn clockwise and ctr. clockwise, marking those lines intersecting the wall. An overlay of the marked starting points defines areas with properties of a scrape‐off layer and areas with field lines ending on one side in the ergodic layer and one side on the wall. The edge plasma can be described by a 2‐D model; the model treats a part of the plasma as that of a conventional scrape‐off layer and another part with “half open” field lines connecting the divertor target plate with the ergodic layer. Calculations of the power flux distribution in the DED‐near field divertor are presented.