Fabrication Technique of the Model Coil for the 40-T Hybrid Magnet Superconducting Outsert

In the High Magnetic Field Laboratory, Chinese Academy of Sciences, a model coil has been fabricated and tested with the intention of developing the manufacturing technique and confirming the research and development routine of the superconducting outsert for a 40-T hybrid magnet. The model coil was layer wound using a cable-in-conduit conductor with small radius due to the restriction of the inner diameter of a NbTi solenoid coil, which will provide a central 7.5-T background magnetic field for the model coil tests. In normal operation, the highest field on the model coil conductor would reach about 12 T. The manufacturing process of the model coil included conductor forming, winding, heat treatment, vacuum impregnation, and assembly. For the purpose of summarizing the whole manufacturing process, in this paper, the important fabrication techniques are introduced and discussed.