An automatic ultrasonic welding process for interconnecting superconducting wires of the CERN Large Hadron Collider (LHC)

The Large Hadron Collider (LHC), the next research tool for particle physics at CERN, is due to start operation in 2005. The main components of the LHC are the superconducting twin-aperture magnets, operating at a temperature of 1.9 K. A large number of auxiliary superconducting wires have to be interconnected in series to electrically feed, at 600 A, the main dipole and quadrupole corrector magnets. To interconnect these wires, an ultrasonic welding process has been developed and compared to the former soft-soldering technique. An industrial ultrasonic welding machine has been adapted and automated to satisfy the reliability and reproducibility. A high strength mechanical junction between wires has been obtained over the operating range from 293 K to 1.9 K. Results of mechanical and electrical validation tests are presented.