Regular patterns in the plasma edge with the ergodic divertor

摘要

The ergodic divertor of Tore Supra is made of of 6 octopolar coils which induce radial perturbations of the magnetic field. Each coil with its heat extraction and particle pumping system is referred to as a module. The divertor volume controlled by this system (20% of the radius) is devoted to the control of plasma-wall interactions. Two regions can be identified in this volume, the laminar layer and the ergodic layer. The laminar layer at the boundary of the plasma is similar to the open field lines volume of the axisymmetric divertor. It is characterized by a regular field line topology and deflection of field lines to target plates (5 per module) located between the current bars. Other laminar layers within the divertor volume, due to local sources or sinks, generate structures that give clear signatures on edge diagnostics measurements. In this paper, these laminar layers are analysed and simple modelling allows one to predict their structure. (authors). 5 refs., 6 figs. (Atomindex citation 27:003853)