Control of contact resistance by strand surface coating in 36-strand NbTi CICCs Original Research Article

The stability and AC loss of NbTi cable-in-conduit conductors (CICCs) is largely determined by the interstrand contact resistance (Rc). Rc is predominantly established by the strand surface properties. Five 36-strand CICCs, fully identical except for the plating of the strand surface or the presence of an internal CuNi shell, are prepared and tested. Beside strands with bare copper surface, chromium, nickel and oxidised stabrite (Sn95Ag5) coatings are applied. The effect of an epoxy curing heat treatment (HT) and electromagnetic loading on Rc is simulated and measured. Applying different strand coatings in NbTi CICCs, offers a broad range in Rc, from 7 to 430 nΩ m, while the interstrand nτʹs vary between 64 and 2 ms.