Cable-in-conduit (CIC) conductors using Nb 3Sn strands are used in ITER toroidal field (TF) coils. The wound TF conductor must be inserted in the groove of the radial plate (RP), which is part of the mechanical structure supporting the large electromagnetic force. Since the available gap between the conductor and RP groove is 0.5~3 mm, the tolerance of the circumferences of the winding and RP groove are +/- 0.023%. Since a tolerance of approximately +/-0.01% is needed for the RP machining, the conductor length of the winding must be controlled with an accuracy of +/- 0.01%. In this study, in order to resolve the above technical issues, the authors performed several trials on winding as the part of the activities in Phase II of TF coil manufacture. In these trials, the accuracy of the conductor length measurement system using the optical equipment was evaluated, and winding trials were performed on a 1/3-scale double-pancake (DP) winding to demonstrate use of the winding system. In addition, the conductor length of the 1/3-scale DP trial winding was evaluated, and the elongation of the conductor due to bending was clarified.
