Joints fabrication in superconducting magnets of SST-1

Steady State Tokamak (SST-1) is a medium sized tokamak being built at Institute for Plasma Research, India to study the plasma parameters. SST-1 machine consists of 16 nos. of superconducting toroidal field (TF) magnets and 9 nos. of superconducting poloidal field (PF) magnets apart from many other resistive magnets to produce and control the plasma. Superconducting TF and PF magnets are made of multifilamentary NbTi/Cu based cable-in-conduit-conductor (CICC). More than 125 nos. of low resistance CICC joints have to be made to complete the superconducting magnet system. The soldered shake hand type joint configuration has been adopted to negotiate with AC and DC losses in the joints. The joint fabrication technology has been developed in house at IPR. The full size prototype joints have already been successfully tested at liquid helium temperature. The joint resistance of ∼3.0 nΩ at 10.0 kA current and 4.2 K has been achieved. The joint fabrication in actual superconducting magnets to be used in SST-1 has already been started. Four of the PF magnets and thirteen of the TF magnets have already been completed with the joints. The joints in remaining magnets will be completed within next 2 months. The paper describes the joint design, joint fabrication method, joint test method and test results, and latest status of the magnets.