Optimization of Nb3Sn Rutherford Cables Geometry for the High-Luminosity LHC

The quadrupole and dipole magnets for the high-luminosity large hadron collider (HL-LHC) upgrade will be based on Nb 3 Sn Rutherford cables that operate at 1.9 K and experience magnetic fields of up to about 12 T. An important step in the design of these magnets is the development of the high-aspect-ratio Nb 3 Sn cables to achieve the nominal field with sufficient margin. The strong plastic deformation of unreacted Nb 3 Sn strands during the Rutherford cabling process may induce non-negligible I c and Residual Resistivity Ratio degradation. In this paper, the cabling degradation is investigated as a function of the cable geometry for both Powder-in-Tube and Restack Rod Process conductors. Based on this analysis, new baseline geometries for both 11 T and quadrupole magnets of HL-LHC are proposed.