Comparison of the DC performance of full- and sub-size NbTi cable-in-conduit conductors

The DC performances of three full- and five sub-size NbTi cable-in-conduit conductors, measured in the SULTAN test facility, are compared. In general, the self-field effect was found to cause sudden take-offs at high currents. In most of the investigated conductors the transition to sudden take-offs occurs for self-field contributions between 0.5 and 0.8 T. In the region of the sudden take-offs, the quench currents of the full-size conductors were found to be far below the critical current expected for the peak magnetic field. This behavior can be attributed to a current unbalance among the strands, which seems to be more pronounced at higher currents.