Deformation Behavior and Degradation on Rutherford Cabling of Nb$_{\text{3}}$Sn Wires

In the production of Rutherford cables, Nb
$_{\text{3}}$
Sn strands are subjected to severe deformation; and to evaluate this degradation prior to cabling, uniaxial rolling with a thickness reduction of ∼15% has often been used. The effects of this deformation on superconducting performance differ significantly between wire designs. In this article, wire deformation behavior is investigated by image analysis of electron micrographs, and the resulting degradation of critical current and residual resistance ratio is quantified, for several designs of internal tin (RRP and distributed tin) and powder-in-tube wire in use or under study at CERN for the HL-LHC upgrade and High Field Magnets program. The suitability of uniaxial rolling as a predictor of cabling degradation is assessed and recommendations are made for improved testing procedures.