Design and Development of Turn Insulation Automatic Wrapping System for CRAFT TF

A principal part of the Comprehensive Research Facility for Fusion Technology (CRAFT) is the toroidal field (TF) coil project, which aims at fabricating a prototype TF coil for China Fusion Engineering Test Reactor (CFETR). The TF coil is composed of 3-D-shaped subwinding packs (sub-WPs) enclosed in a stainless coil case, and the conductor core of medium and high field sub-WPs is Nb
₃
Sn, following the “Winding & Reaction” manufacturing process. After heat treatment of the conductor, turn insulation will be automatically wrapped. Strictly restricted by the brittleness of the heat-treated Nb
₃
Sn, the strain must be controlled during the wrapping process. Presented in this article is a description of the CRAFT TF coil and its turn insulation structure, followed by descriptions of the structural design of the wrapping unit and mathematical models about wrapping control of the wrapping machine. Turn insulation wrapping trials are performed with one-fourth part of the wrapping unit, and tapes with a fixed width and a uniform steel tube are used as specimens, verifying the correctness of the structure and models. The one-fourth part of the wrapping unit has been fabricated in March 2022 and it is foreseen that the fabrication will be finished in June 2022.