Current Center Line Integration in the Manufacturing Process of the ITER Toroidal Field Coils

The first ITER's European Toroidal Field Coil (TFC) is going to be assembled in 2019. The TFC is composed mainly by the superconducting Winding Pack (WP - manufactured in Europe), and the Coil Cases (TFCC - manufactured in Japan), which provide structural integrity to the magnet and offer interface connections with the rest of the machine. Dimensional measurements and other manufacturing data are taken during the WP manufacture and are used to reconstruct the Current Centre Line (CCL), which is defined as the barycentre of the as-built conductors inside the WP. The CCL is useful to characterize the magnetic field generated by the magnet, and its monitoring and control can minimize the Error Field during ITER operation. Fusion For Energy (F4E) developed a method to calculate the CCL using manufacturing data. Since the CCL represents how different the WP is manufactured from its nominal conductor layout, this deviation can be corrected where there is need of a more controlled magnetic field shape, namely in the straight inboard area of the D-shaped tokamak. That is why each WP position inside its respective TFCCs is optimized, compensating the deviations detected and maintaining an allowable gap between components for the subsequent welding and resin filling operation. This paper presents the strategy followed by F4E to calculate the CCL and optimize the WP position inside the TFCC, by means of extensive CAD and CAE modelling activity. It explains also the data management process developed and followed to ensure configuration control of all the data inputs and outputs, coming from different sources and formats, and details the successful insertion operation on the first ever ITER TFC coil manufactured in Europe, and how in the future the updated CCL coil position will be used to define the final TFC machining, after the welding and gap filling operations.