Effect of Current Distribution on the Stability of a Triplet NbTi/Cu Superconductor

A triplet NbTi/Cu superconductor, high current density superconducting strands for a cable-inconduit conductor (CICC), was used to study the influence of current distribution on stability within the triplet. The initial current distribution among superconducting strands was controlled in terms of a resistive heater wound on the exterior of each strand. The minimum quench energies (MQE) were measured with different initial current distributions within the triplet. We experimentally confirmed that MQE for the triplet was not less than three times MQE for a strand when the transport current of the strand was larger than its minimum propagating current. In addition, MQE changed with the difference of initial current distribution among the strands. This reason is discussed from the viewpoint of the ratio of the triplet's total transport and critical currents, and the difference between the transport current of heated strand and its minimum propagating current.