Imaging Challenges for ITER Plasma-Facing Component Protection

The ITER actively cooled tokamak is the next-generation fusion device that will allow study of the burning plasma over hundreds of seconds. ITER plasma-facing component (PFC) real-time protection will be mandatory to minimize operational risks as water leaks and critical heat flux lead to degradation of PFCs. The protection systems routinely used on Tore Supra (TS) or JET are based on infrared (IR) imaging systems controlling and monitoring the power load on the PFCs through surface temperature measurements. Thanks to TS expertise in actively cooled tokamak and long-pulse operation, three urgent research and development domains are discussed in this paper addressing the feasibility and the performance of the PFC protection function for the new and harsh environment of ITER: (a) the understanding of IR signals in a reflective environment using a physics-based light model simulation; (b) a PFC protection data processing architecture for event detection and identification; and (c) the feasibility, performance, and prototyping of the first optical component of the imaging systems - actively cooled, facing the plasma - which will impact the image quality and therefore PFC protection performance.