Effect of Core Width, Placement, and Condition on Calorimetrically Measured AC Loss and Interstrand Contact Resistance of Stainless-Steel-Cored $\hbox{Nb}_{3}\hbox{Sn}$ Rutherford Cables

Calorimetric measurements of AC loss were made on Nb3Sn Rutherford cables furnished with cores of widths 4.5, 5.2, and 10.8 mm in the face-on (FO) and edge-on (EO) orientations of the applied AC field. The resulting FO-measured effective interstrand contact resistances, R
_perp,e,f,f.
, were compared with that of the uncored cable after which it was noted that although the uncored R
_perp,e,f,f.
agreed well with those of previously measured cables, the cored values -0.3 to 8 muOmega were lower than expectation. The relatively low -R
_perp,e,f,f.
s are attributed to (i) drifting of the narrower cores to one edge of the cable (ii) shrinkage of the effective width of the widest core as a result of severe texturization. After correcting for these deficiencies the projected R
_perp,e,f,f.
for the widest-core cable moved closer to the range of values expected for a full-width-core Nb
₃
Sn cable.