Design overview of ex-vessel components for the Wide Angle Viewing System diagnostic for ITER Equatorial Port 12

Highlights: • The manuscript shows the preliminary opto-mechanical design of the ex-vessel components for the wide angle viewing system (WAVS) for ITER equatorial port 12. The design of the diagnostic in this port is well advanced since it has to be operative for the ITER first plasma (scheduled for the end of 2025). • The WAVS ex-vessel optics relay the exit image of the port plug at the vacuum window up to the cameras placed inside a shielded cabinet in the port cell. • The ex-vessel optics based on mirrors and refractive elements are arranged in opto-mechanical modules that can be assembled, integrated and verified as independent sub-systems. • The optical hinge is the first component of the ex-vessel optical chain that aims to compensate the differential motion between the vacuum vessel and the building, in normal operation and baking. The mechanical assembly and operation of this critical component is also presented in the manuscript. The ITER equatorial visible and infrared Wide Angle Viewing System (WAVS) provides surface temperature measurements of plasma facing components by infrared (IR) thermography being one of its main roles to protect them from damage. It also images the plasma emission in the visible range. The diagnostic, which comprises 15 lines of sight distributed in four equatorial ports (3, 9, 12 and 17), will contribute to Machine protection, Basic control and Physics analysis in ITER. The design of the diagnostic in the equatorial port 12 (EP12) - comprising three lines of sight - is currently being developed within a Framework Partnership Agreement through a Specific Grant granted by F4E to the Consortium formed by CEA, Ciemat and Bertin Technologies. EP12 has to be operative for the ITER first plasma. The overview of the WAVS opto-mechanical design for the ex-vessel components in EP12 will be presented in the paper. The ex-vessel optics are composed of mirrors and refractive elements which relay the exit image of the port plug at the vacuum window up to the cameras placed inside a shielded cabinet in the Port Cell. The image relay through the Interspace, Bioshield and Port Cell has to cover a length of almost 10 m in order to reach the detectors. The refractive elements are arranged in sub-assemblies (optical modules) mechanically mounted in barrels and next assembled on a support structure. The assembly of these modules on site will be also presented in the paper. Furthermore, the Optical Hinge which is the first component of the ex-vessel optical chain (formed by two folding mirrors) aims to compensate the differential motion between the vacuum vessel and the building, in normal operation and baking. The mechanical assembly and the operation of this component will be also described in the paper.