Void fraction effect on AC loss in saturation regime for NbTi CIC conductor

A superfluid helium calorimetric technique (the underlying principle of the NHMFL TACL Facility) was used to perform AC loss measurements on NbTi cable-in-conduit conductor samples. AC loss tests have been performed over a range of field variation rates, high enough that the saturation regime is obtained and low enough that hysteresis losses are significant. From these measurements, the effective coupling current time constant of the CICC is determined, and the losses in the saturation regime are used to determine the effective radius of the saturated cable stage. The comparison of time constants and saturation radius as a function of the void fraction of the CICC yield to a better understanding of saturation regime in multi-stages conductors.