Operating space of the Dynamic Ergodic Divertor for 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 has been laid out for the plasma reference conditions tau(res) (q = 3) and beta(pol) = 1. The operational space of DED is analysed here. It has been shown that a sufficient edge ergodization can be reached for all relevant,a values (0 less than or equal to beta(pol) less than or equal to 2). BY Shifting the resonance layer close to the edge, the degree of ergodization can be substantially increased (by about a factor of 4). The power supplies allow a superposition of the base n = 4 mode with the n = 2 mode at arbitrary amplitude ratios, providing a partial decoupling of the perturbation amplitude and its penetration: by an admixture of 20% of the n = 2 mode, the diffusion coefficient for the magnetic field lines is significantly increased. Analyses of the operational space are carried out by using both novel asymptotic and mapping methods.