Scrape-off layer turbulence and transport in the wide divertor heat-flux width simulations of ITER*

Recent simulations [1] with the gyrokinetic turbulence code XGC1 have predicted that the midplane-projected heat-flux width on full-field ITER will be much wider (~6mm) than the expected value from a multi-machine experimental scaling (<1mm) [2]. This result would greatly open the operational space of ITER, and as such a more fundamental understanding is warranted in to why the simulation departs from the experimental scaling. Heuristic scaling arguments suggest that the main reason for the difference is that in the full-field ITER the nonlinear edge turbulence plays a more dominant role in setting the heat-flux width. This work will present a more detailed look at the turbulence characteristics of this ITER simulation in comparison with simulations on low-field ITER and devices such as C-Mod, to begin to understand the mechanisms at play. Beyond typical turbulence characteristics, a focus will be given to the turbulence along the entire scrape-off layer, including through the divertor region.

[1] C.S. Chang, et. al., Nucl. Fusion 57 (2017) 116023.

[2] T. Eich, et. al., Nucl. Fusion 53 (2013) 093031.