US Patent 6973708 Method for reducing AC loss in superconducting coils

A method for reducing ac loss in a superconducting coil of cable-in-conduit type superconductor made from chrome-coated compound superconducting strands, characterized in that when a superconducting coil is produced by the wind-and-react technique, bending or twist strain is applied in an amount of 0.15˜0.3% to the conductor cable portion after it has been heat-treated to form the superconducting compound, thereby separating the individual superconducting strands the chrome coat on which sintered as the result of heat treatment and further characterized in that the applied bending or twist strain is thereafter reverted to 0.1% or less, thereby reducing the ac loss of the superconducting coil.