Numerical modeling of impurity powder injection in W7-X

This is the authors' abstract. We don't add key points for this paper.

In this work, we present numerical simulation results of powder injection in W7-X using the EMC3-EIRENE and DIS codes. First, we model powder injection experiments performed in W7-X with the Probe Mounted Powder Injector. The simulation results qualitatively agree with visible imaging measurements. Secondly, we perform predictive simulations to guide the installation of an Impurity Powder Dropper in W7-X, allowing to choose in between several available non-vertical ports to maximize the amount of powder penetrating into the plasma, as well as the verticality of the port, to minimize sticking of the powders in the in-vessel stainless steel guiding tube. Port AEM41 is selected as the best candidate for IPD installation. The robustness of the simulation results has been verified for different plasma densities, powder materials and sizes, powder friction coefficient and changes in the plasma flow. • Impurity powder injection experiments in W7-X using the Probe Mounted Powder Injector are modeled with the EMC3-EIRENE and DIS codes. • The simulations results agree qualitatively with experimental measurements from visible cameras. • EMC3-EIRENE-DIS simulations are used to guide the installation of an Impurity Powder Dropper on W7-X. • Port AEM41 is chosen as the best option, maximizing the powder penetration into the plasma while minimizing concerns related to non-verticality of the powder guiding tube.