Practical superconductors for accelerators - cables

All superconducting accelerators to date have used magnets wound from Rutherford cable. This second lecture describes why we need cables, the different types of cable and how they are manufactured. In changing fields, the wires in a cable can be coupled via the contact resistances between them. This coupling, which depends strongly on field orientation, adds to the total magnetization and thus to the field error produced in a magnet made from the cable. Non-uniform distribution of current between wires in the cable can cause premature quenching of the magnet and also produce the effect known as ‘snap back’, which is a sudden change in error field at injection.