Overview of core impurity transport in the first divertor operation of Wendelstein 7-X

Abstract

The impurity transport at Wendelstein 7-X during its most recent campaign is characterized and documented for a variety of different plasma scenarios. An overview of its dependence on several quantities is given, which allows identification of transport regimes and the major driver for impurity transport. Beyond this, a comparison with the impurity behavior in other fusion devices is now possible. In contrast to other stellarators, no density dependence of the impurity transport has been found. Additionally, the influence of the turbulence contribution to the overall transport is reflected in the dependence on various parameters, e.g. turbulent diffusion and density fluctuation amplitudes. With this database approach, one can now also apply scaling laws to make extrapolations about the impurity confinement in future plasma scenarios.