Nuclear technology aspects of ITER vessel-mounted diagnostics

Vayakis, G.*; Bertalot, L.*; Encheva, A.*; Walker, C.*; Brichard, B.*; Cheon, M. S.*; Chitarin, G.*; Hodgson, E.*; Ingesson, C.*; Ishikawa, Masao; Kondoh, Takashi; Meister, H.*; Moreau, P.*; Peruzzo, S.*; Pak, S.*; Prez-Pichel, G.*; Reichle, R.*; Testa, D.*; Toussaint, M.*; Vermeeren, L.*; Vershkov, V.*

ITER has diagnostics with machine protection, basic and advanced plasma control, and physics roles. Several are embedded in the inner machine component region. They have reduced maintainability compared to standard diagnostics in ports. They also endure some of the highest nuclear and EM loads of any diagnostic for the longest time. They include: Magnetic diagnostics; Steady-state magnetic sensors on the outer vessel skin; Bolometer camera arrays; Microfission chambers and neutron activation stations to provide key inputs to the real-time fusion power and long-term fluence measurements; mm-wave reflectometry to measure the plasma density profile and perturbations near the core, and the plasma-wall distance and; Wiring deployed around the vessel to service magnetics, bolometry, and in-vessel instrumentation. In this paper we summarise the key technological issues for each of these diagnostics arising from the nuclear environment, recent progress and outstanding R&D for each system.