Critical current measurement of prototype NbTi cable-in-conduit conductor for JT-60SA

The prototype NbTi conductor of JT-60 Super Advanced (JT-60SA) was fabricated and tested to confirm the capability of National Institute for Fusion Science (NIFS) facility for qualification tests of real conductors and to envisage the performance of real conductors. The conductor which length is 3 m was formed to racket shape sample without internal joint to minimize the effect of joint. The circular part of sample which conductor length is longer than final twist pitch was experience maximum magnetic filed. The current sharing temperature (Tcs) in the range of 4.8–7.0 T, ≤20 kA could be measured indicating that the NIFS facility is suitable for the qualification tests of real conductors. The degradation of Tcs was only 0.01–0.08 K from expectation values at 20 kA. The nickel plating, central spiral and cable compaction and forming process did not cause the large performance degradation.