High-frequency operation of the Dynamic Ergodic Divertor (DED)

After the introduction of the experimental options with the DED and after a discussion of the static aspects of the ergodic and laminar zones, the dynamic features of the rotating DED field are emphasised. The rotating perturbation field induces a shielding current which is modelled under different assumptions. A result of the interaction of the shielding current with the external one is the transfer of a torque from the DED-coils to the plasma. The location of the maximum of this transfer function with respect to the frequency depends critically on the width of the shielding current. From the transferred torque, at first the toroidal velocity of the plasma is computed and from the poloidal force component, the radial electric field is estimated assuming a revisited neoclassical theory. (author)