Basic Design and Progress of the Spliced Joint for CFETR TF Coil

High-performance superconducting joints are essential for the continuous and stable operation of superconducting magnet systems to generate stable magnetic fields, because the local heating from resistive losses can cause the superconductor to enter an unstable regime and result in quench. The China fusion engineering test reactor has five internal joints for each toroidal field coil. To provide a lower heat load of the joints to the cryogenic system, the direct current (dc) resistance of the internal joint connection must be below 0.3 nΩ. At the same time, the structure of the joint jacket should be convenient for winding. The internal joints must fit a space envelope equivalent to the original conductor cross section and must have enough structural strength and a low pressure drop. In the basic design, two trial joints were manufactured and tested at ASIPP. This article provides a description of the design, simulation, and manufacturing process of the trial joint, and finally obtained the test results with electrical resistances of 0.057 and 0.076 nΩ.