AC losses in a prototype NbTi cable for LHC dipole magnets

In this paper loss measurements on a prototype NbTi cable for the Large Hadron Collider dipole magnets are presented. The cable is meant to be used for the outer layer of the magnets. It is a trapezium-shaped (key-stoned) Rutherford cable. The experimental results were obtained in a Twente test facility. Magnetization loss measurements as well as transport current loss measurements were performed. The results are compared with classical loss models. From the magnetization experiments the coupling time constant of the cable at different magnetic fields can be obtained. It is also possible to estimate the critical current density from these measurements. The critical current and the effective transverse resistivity are important for calculations concerning the loss during ramping the magnetic field and the field disturbance due to shielding currents in the filaments and to the coupling currents.