Systematic multi-machine analysis of the exhaust time-dependent behavior in tokamaks

This work presents an overview of experimental investigations of the exhaust dynamics in TCV, MAST-U, ASDEX-Upgrade, WEST, DIII-D, and JET. Using various different perturbations such as gas-injection, impurity injection, and power modulations and corresponding responses on various outputs is analyzed. From these experiments, a clear picture arises on properties of the exhaust dynamics across machines. Particularly, we observe that the scrape-off layer equilibrates on fast time-scales and strong similarities across scenarios (H-mode, L-mode), injected species, and injection locations. On the other hand, we see clear differences when analyzing different exhaust properties. This is all summarized in a database that is for the validation of dynamic exhaust models for reactor design. Moreover, some measurements presented have formed the basis for systematic exhaust control on the considered devices.