Fractal structure of the magnetic field in the laminar zone of the Dynamic Ergodic Divertor of the Torus Experiment for Technology-Oriented Research (TEXTOR-94)

Magnetic field properties at the plasma edge in the Dynamic Ergodic Divertor (DED) for the Torus Experiment for Technology Oriented Research (TEXTOR-94) [Fusion Eng. Des. 37, 337 (1997)] have been studied. This is done by using a generalized symplectic mapping method of integration of field line equations. It is shown that by the radial shift of the resonant magnetic surfaces implemented by change of the plasma current (or the toroidal field) one can strongly vary the plasma edge regimes from the ergodic zone dominated one to the laminar zone dominated regimes in which the field lines with short wall to wall connection lengths are predominant. The embedded in the laminar zone narrow ergodic zones have fractal structures which are investigated in detail. The fractal structures of the magnetic footprints on the divertor plate are also studied. (C) 2001 American Institute of Physics