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• 3D ANSYS Maxwell FEM model developed for the EM analysis of the IAM at FDR level. • ISS modelled to calculate the flowing eddy currents between IAM and structure. • Found presumed convergence errors in sharp inner boundary corners of Maxwell models. • Calculated IAM forces are not design driving so do not compromise the final design. The ITER Visible and Infrared Wide Angle Viewing System (WAVS) is a diagnostic aiming to optically monitor the tokamak first wall and divertor for machine protection, plasma control and physics analysis. The Interspace Afocal Module (IAM) is a refractive optical system, being one of the WAVS components located in the Interspace area. In order to assure the optical performance, the IAM has to withstand all the relevant loads defined for the Final Design, including the electromagnetic (EM) loads developed in the Interspace area under EM events. Volumetric forces during transient EM events arise from the interaction of the background magnetic field with the eddy currents induced in the conductive components when they experience time-varying magnetic fields. In case of Category III and IV loads, including load combinations with certain Major Disruption and Vertical Displacement Event cases, the IAM integrity has to be ensured since its structure is classified as Safety Relevant. The EM volumetric loads are calculated through a 3D Finite element model and will serve as inputs for the later structural analysis. The paper summarizes the EM analysis of the IAM, performed by CIEMAT, to validate its Final Design. [ABSTRACT FROM AUTHOR]

The equatorial visible and infrared Wide Angle Viewing System (WAVS) for ITER is one of the key diagnostics for machine protection, plasma control and physics analysis. To achieve these objectives, the WAVS will monitor the surface temperature of the Plasma Facing Components (PFCs) by infrared (IR) thermography (3–5 μm range) and will image the edge plasma emission in the visible range. It will be composed of 15 lines of sight installed in four equatorial ports (no. 3, 9, 12 and 17) in order to survey at least 80% of the overall area of the vacuum vessel. This paper presents the optical design of port-plug which has to cope with both challenging performances (wide field of view, wide temperature range 200–2000 °C, high measurement accuracy required lower than 20%) and severe constraints such as harsh nuclear environment, complex interfaces. Indeed the optical components are embedded within the ITER Diagnostic Shielding Module, DSM, which is not usual for diffraction limited instruments. It is shown that nominal optical performance of the Port-Plug are limited by the diffraction only. In operation, this design has demonstrated its superiority on the former ones since it is much less sensitive to tolerance variations. [ABSTRACT FROM AUTHOR]

• Piezoelectric technology is suitable for working under ITER conditions, with a good behavior in radiation environments. • The tested piezo actuator can work after being irradiated, although its maximum speed has been reduced by around 12%. • The controller to drive the piezo actuator can be located up to 110 m away, to keep electronics away from radiation. The Wide Angle Viewing System (WAVS) for ITER is a major diagnostic for machine protection, plasma control and physics analysis. The diagnostic will measure the surface temperature of the plasma facing components by infrared thermography being one of its main roles to protect them from damage. It will also image the plasma emission in the visible range. The full system is composed of 15 lines of sights located in four equatorial ports (3, 9, 12 and 17). As part of the ex-vessel optics, the first element of the optical chain is the Optical Hinge (OH). It is constituted by two folding mirrors which face the port plug exit optical beam. The mission of this component is to compensate the differential motion between the vacuum vessel and the building, during normal operation and baking. This function will be performed by means of a piezo actuator coupled to the OH upper mirror (and a set of reference switches) to drive the vertical displacement of the mirror in order to get the desired alignment position of the optical beam. The piezo actuator has been identified as the main critical item of the OH what has motivated the fabrication of an OH prototype (for one line of sight) aimed at performing a set of tests to validate the piezo actuator under operation conditions. The tests have consisted in the characterization of the piezo actuator behavior with the nominal load after being irradiated to 272.40 kGy of total accumulated gamma dose, which is the dose expected in ITER. Moreover, additional tests have been conducted to find out the influence of the cable length from the piezo actuator to the controller in the performance. A description of these tests and the results obtained will be presented in the paper. [ABSTRACT FROM AUTHOR]