Control of contact resistance by strand surface coating in 36-strand NbTiCICCs

The stability and AC loss of NbTi cable-in-conduit conductors (CICCs) is la rgely determined by the interstrand contact resistance (R-c). R-c is predom inantly established by the strand surface properties. Five 36-strand CICCs, fully identical except for the plating of the strand surface or the presen ce of an internal CuNi shell, are prepared and tested. Beside strands with bare copper surface, chromium, nickel and oxidised stabrite (Sn95Ag5) coati ngs are applied. The effect of an epoxy curing heat treatment (HT) and elec tromagnetic loading on R, is simulated and measured. Applying different str and coatings in NbTi CICCs, offers a broad range in R-c, from 7 to 430 n Om ega m, while the interstrand n tau 's vary between 64 and 2 ms. (C) 2001 El sevier Science Ltd. All rights reserved.