Development of a Magnetic Diagnostic Suitable for the ITER Radiation Environment

Abstract— Magnetic diagnostics of the ITER tokamak must fulfill demanding specifications, because their accuracy and reli- ability affects margins to the machine engineering limits and therefore operational flexibility. This paper describes the chal- lenging issues related to the implementation of the magnetic diag- nostics in a tokamak environment. We focus on nuclear radiations as they can significantly affect the measurement through Radia- tion Induced Electromotive Force (RIEMF) or Thermally In- duced Electromotive Force (TIEMF). Thermal modeling of mag- netic sensors and associated design studies are also reported as the thermal gradient in the sensors must be reduced to avoid TIEMF. Alternative magnetic sensors such as fiber optic current sensors (FOCS) or steady state magnetic field sensors are also discussed because they serve as a backup to the usual inductive magnetic measurements. We conclude by a brief review of the development needs for magnetic diagnostics..