The effect of Ti conduit on the critical current in (NbTi)/sub 3/ Sn cable-in-conduit conductors

The authors investigated the effect of Ti conduit on the critical current in (NbTi)/sub 3/Sn cable-in-conduit conductors in comparison with stainless steel and copper-nickel alloy conduits. Ti has a coefficient of thermal expansion closely matching (NbTi)/sub 3/Sn and is expected to prevent the compressive thermal prestrain introduced in (NbTi)/sub 3/Sn filaments. As samples, two kinds of conductors were prepared, one consisting of seven (NbTi)/sub 3/Sn strands and the other of 36 (NbTi)/sub 3/Sn strands. The (NbTi)/sub 3/Sn strands produced by a bronze process had a diameter of 1.0 mm and a copper ratio of 2. The experimental results indicated that the critical current density in conductors with a Ti conduit and void fraction in the range of 5-46% nearly matched that of a single strand. From these results, Ti appears to be attractive as a practical conduit material for (NbTi)/sub 3/Sn cable-in-conduit conductors.<
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