Preliminary study of the influence of DED on carbon radiation and transport in the TEXTOR tokamak

Changes on transport and radiation properties of intrinsic carbon under the influence of the Dynamic Ergodic Divertor depend on the modal composition of the induced error field. For 12/4 mode operation, significant carbon screening is not observed up to half of the nominal DED maximum current achieved so far. On the contrary, for 3/1 DED operation the very efficient mechanism of expulsion of highly ionized carbon ions, observed to occur locally at the foot prints of the 3/1 helical structure and explained in terms of frictional forces, leads to a global carbon decontamination of the central plasma. This result has been established using a new multi-chord diagnostic, which allows to distinguish global from local carbon behavior.