Development of the iron-based superconducting coils for high magnetic field application

•Development of the IBS coils for high magnetic field application in details.•Some defects in the coils have been discovered during testing, and technological improvements are applied in fabrication of coil accordingly, the performance of new coils is greatly improved at last.•Experiences are gained for large scale magnet such as VPI is essential for large scale magnet. This paper mainly focuses on the development of iron-based superconductor (IBS) coils made by a wind and react method. IBS is brittle after heat treatment, and little mechanical damage may reduce the performance of the tapes and coils. We developed a type of IBS coil with single or double pancake, which exhibits little performance reduction after some technological improvements. High-performance Ba122/Ag/AgSn tape and stainless steel (SS) frame are used for winding the coils. G10 steeve is chosen to carry the coil and connecting to the current lead during test. The manufacturing processes for IBS coils, including winding, fixation, heat treatment, welding and epoxy impregnation, are introduced in detail in this paper. Meanwhile, some defects in the coils have been discovered during testing, and we come up with some technological improvements accordingly, the performance of new coils is greatly improved.