2023 Volume 18 Pages 2405009
In Japan, National Institutes for Quantum Science and Technology (QST) has the responsibility to develop nine toroidal field (TF) coils, each of which consists of a winding pack (WP) and coil case for the ITER project. The WP consists of seven double-pancakes (DPs), which consist of conductors inserted into D-shaped radial plates (RPs). Although a WP is significantly large (14 m high and 9 m wide), the position of the current center line of the WP must be controlled within a few millimeters. Therefore, numerous technical challenges arose in DP and WP manufacturing. Herein, in the RP manufacturing, the optimization of welding and machining procedures, and accurate manufacturing techniques were established. Subsequently, all RPs were fabricated around the flatness errors of 1 mm from the nominal. In cover plate (CP) welding, the welding procedure was optimized so that a good DP flatness after CP welding was achieved. In the WP insulation, by developing a method to insulate a WP while applying compression, the dimensions within errors of a few milli-meters is achieved in all of WPs. Consequently, all nine WPs were successfully completed for TF coils in Japan in March 2022.
