Modeling of tungsten impurities with gyrokinetic bundles in the XGC code for the study of JET-ILW and WEST physics

Tokamak physics in a tungsten environment is a critical topic of research, as tungsten impurities are found to degrade the confinement time of tokamaks. This physics will be studied with the XGC code by simulating the whole device plasma with multiple gyrokinetic ions [1,2]. To take into account the many ionization states of tungsten, we have developed a new model that permits to model 50 ionization states of tungsten with only 7 gyrokinetic bundles and their atomic interactions [3]. Bundles are commonly used by fluid code, but not by gyrokinetic codes. The atomic interaction rates for the gyrokinetic bundles are computed from ADAS data. The motivation for including the atomic interactions comes from preliminary simulations where we observed that large (df/f~1) amplitude asymmetries, whose poloidal orientation depends on the charge number Z, form in the pedestal and edge regions. Furthermore, these different asymmetries drive particle fluxes of different directions and lead to the accumulation of tungsten in the pedestal. We will present our model and preliminary results for JET-ILW pedestal physics, as well as a new application of the XGC code to the study of WEST edge physics.

[1] Dominski et al (2019) Journal of Plasma Physics 85 (5) 905850510

[2] Dominski et al 27th IAEA Fusion Energy Conference (FEC 2018) 22–27 October 2018, Gandhinagar India

[3] Dominski et al 46th EPS Conference on Plasma Physics, 7-12 July 2019, Milan Italy.