DC performance of a Nb-Ti Rutherford cable: Measurements and model computations

Abstract High-current superconducting conductors are widely used in fusion magnets and high energy accelerators. In order to carry out experimental research on new high-current conductors, we have developed a new test facility for their critical current (Ic) measurements. We have used this facility to test a Nb-Ti Rutherford cable three times. Premature quenches were detected for the first two tests. They were mainly caused by small mechanical motion of the cable sample. After the mechanical support enhancement of sample, the critical current was successfully measured at the third time. The fixing structures of sample for these three tests are described and compared in consideration of transverse pressure applied to sample during different stages and the transverse displacement of cable after powering. The transverse pressure of first two tests reduced after cooling down and were not strong enough to withstand Lorentz force. Assuming uniform current distribution among strands and considering the inhomogeneous self-field, a model is developed to predict the V-I characteristics of the Rutherford cable using the measured properties of the strand. The expected Ic of cable under different background magnetic field are consistent with the measured results.