CFETR Nb₃Sn coil in heat treatment deformation analysis and fixture designing

Abstract

According to the research, it is found that the Hybrid Magnet coils, JT-60SA, ITER and CSMC coils are fixed by coils during heat treatment in order to prevent the coils deforming due to the release of residual stress. Since the penultimate process step of CFETR CSMC Nb3Sn coil manufacturing process is the final assembly of the coil, the theoretical value of the initial unilateral gap between Nb3Sn inner and outer coils is 27.4mm, and the theoretical value of the initial unilateral gap between Nb3Sn outer coil and NbTi coil is 50mm. This gap will be reduced in each process of coil manufacturing process. In order to successfully assemble the coil, it is of great significance to analyze and develop a set of tooling to reduce coil deformation in heat treatment process.