Practical Low-Temperature Superconductors for Electromagnets

After a brief history of the main discoveries in applied superconductivity, the structure and properties of NbTi and Nb$_{3}$Sn are discussed. Then, we explain why low-critical-temperature superconductors are produced under the form of multifilament composites, and we review the manufacturing processes of NbTi and Nb$_{3}$Sn wires. We follow by a description of the transition from the superconducting to the normal resistive state of multifilament composite wires and we detail their magnetization properties. Last, we present the most commonly used cable configurations and we provide simple formulae illustrating with a few examples the computation of losses generated under time-varying magnetic fields.