The influence of divertor target plates on the magnetic field of the dynamic ergodic divertor of TEXTOR-94

The dynamic ergodic divertor DED is under construction as a novel tool for TEXTOR-94 to control transport at the plasma edge and possibly also plasma rotation. The DED will be operated with DC and AC currents at frequencies between 50 Hz and 10 kHz. The efficiency of the magnetic field in the plasma region especially at frequencies above 5 kHz is influenced by the complete structural arrangement in the vicinity of the DED coils. The main influence is given by the graphite tiles. For the design of the coil arrangement and the layout of the power supply the knowledge of the shielding effect especially of the divertor tiles on the magnetic field strength is important. Furthermore the knowledge of induced currents in the tiles as function of the tile dimensions and the resulting temperatures is necessary in order to optimize their dimensions and to calculate the forces for the layout of the mechanical design.