From its location inside of the toroidal field coil case, tucked safely into guiding grooves and "frozen" in place by resin, the role of each CER coil is to measure the toroidal current flowing inside the ITER plasma, a key diagnostic measurement with implications for operation safety and plasma control.
You'll have to take our word for it. Under the protective wrapping, and inside of the sealed steel case, a critical diagnostic device for the measurement of plasma current has been successfully installed—a continuous external Rogowski (CER) coil. Toroidal field coil #8 (TF8) arrived at ITER on 12 March 2021.
The second set of CER coils has been fully integrated to toroidal field coil #2 (TF2) in Japan, and will be shipped to the ITER site after the manufacturing scope of this coil is completed. For TF14, the CER detector cables were already placed inside the toroidal field coil case manufactured in Japan; further cable connection, wiring, and resin filling will take place at SIMIC, the toroidal field coil integration facility in Europe.
These small rope-like continuous external Rogowski (CER) coils measure the total electric current flowing in the ITER plasma independently from their location inside of the cases of three toroidal field coils, including TF8, procured by Japan.