Gyrokinetic modeling of tungsten transport and radiation in WEST and ASDEX Upgrade plasmas: towards the kinetic modeling of ITER physics*

Understanding the impact of tungsten on tokamak performance and its mitigation by low-Z impurities is key to the success of ITER operations. A novel self-consistent gyrokinetic model, integrated into the XGC code [1,2], has been developed to comprehensively analyze tungsten transport and radiation. In this model, the tungsten ions are represented by a few bundles, with their fractional abundance determined by the atomic balance between ionization and recombination processes derived from ADAS rates [3]. The electron cooling by tungsten radiation is also derived from ADAS rates. This new model enables the study of tungsten radiation, transport dynamics, and interactions with low-Z species. Two complementary tungsten studies will be presented. First, we study the impact of nitrogen on the collisional and turbulent peaking factors of tungsten in a WEST plasma. Second, we explore the intricate interplay between collisional and turbulent transport in an H-mode plasma scenario of ASDEX Upgrade containing boron impurities.  Analysis of tungsten radiation with synthetic diagnostics will be discussed, along with the temperature screening effect in ITER-relevant plasmas.

[1] J Dominski et al. J. Plasm. Phys. (2019)

[2] J Dominski et al. Phys Plasmas (2024)

[3] https://www.adas.ac.uk

[4] J Dominski et al. "Influence of nitrogen impurities on the tungsten peaking in total-f gyrokinetic simulations of an ohmic plasma of WEST" to be submitted