Technology and Tooling to Manufacture Low-Ohm $(< 2 \hbox {n}\Omega )$ Electrical Joints of the ITER PF1 Coil

According to the technical specification for the PF1 coil, niobium-titanium “cable-in-conduit” conductors are to be connected into a single electric circuit using low-ohm electrical joints. The joint design is proposed by the International Thermonuclear Experimental Reactor Organization. It is required to develop special equipment and technology for the removal of a stainless steel (SS) jacket from a superconducting cable and for the connection of the cable with a resistance of less than 2 nΩ in the range of operating temperatures and magnetic fields. The main features of the technology are the following. 1) Explosion welding is used to make bimetal plates of SS and copper with a thickness up to 15 mm. 2) Computer numerical control machines are used for termination box manufacturing. 3) A portable milling machine is used to remove the SS jacket without damages of the PF1 conductor cable. 4) A specially made machine compacts cable strands around an SS tube. 5) Using moveable sandblasting equipment, it is possible to carry out abrasive treatment of the cable to remove nickel coating from the strands without damages. 6) A special technique is used for electrolytic tinning of cable and termination box surfaces without an electroplating bath. These techniques and equipment are used for manufacturing of several mockups, including a full-scale mockup. The results of the first tests are mentioned in this paper.