Current Center Line Calculation Method and Results for ITER Poloidal Field Coils

Abstract

Three out of six Poloidal Field Coils (PFC) are already delivered to the ITER Organization. The PF Coils are built winding, impregnating, and vertically stacking double pancakes (DPs) of NbTi Cable-in-Conduit conductors into a Winding Pack (WP). Later, the Winding Pack (WP) is impregnated for ground insulation and clamping devices are installed for structural support and interface with the rest of the ITER machine. One of the main parameters characterizing the PFCs is the Current Centre Line (CCL), defined as the barycentre of its WP conductors. Ideally, the CCL would be in the WP's symmetry plane but due to solutions in the construction design and manufacturing deviations, it may vary. Double Pancakes (DPs) may be wound with different dimensions, or a deviation during their stacking would cause a misalignment of all the conductors contained in that ill-positioned DP, affecting the CCL. The manufacturing process starts with the conductor winding and insulation, forming a DP. The DP is then impregnated with resin and a scan of its surface is used to reconstruct the DPs virtually. The DPs are then stacked, forming a WP, and measurements of points on the surface are used to recreate the process virtually. Finally, the WP is insulated and impregnated with resin. At this stage, both surface scans and point measurements are used to align the WP in the coordinate system of the ITER machine. This paper explains the process to calculate the CCL of the three first PF Coils using manufacturing data, defining the uncertainty associated with the calculation and comparing against the target tolerances defined for the proper ITER machine operation.