Thermodynamic modeling of enhanced superconducting cable insulation for the proposed upgrade of the LHC inner triplet Nb-Ti quadrupole magnets

Abstract

The results of thermal modeling of a new cable insulation scheme proposed for a new set of larger aperture Nb-Ti inner triplet quadrupole magnets for LHC upgrade are presented. The new insulation scheme, so called enhanced insulation, is aiming at a more efficient heat transport from the coil to the helium bath. This scheme relies on leaving open helium paths between the bath and the cable. This report summarizes a detailed study of helium cooling channels efficiency in enhanced cable insulation as well as the heat evacuation schemes with respect to different cable insulation winding scheme. A numerical calculations and validation with experimental results showed that heat transfer efficiency of enhanced insulation is reduced, indicating that effective helium channels cross-sections are significant smaller than the nominal ones. The ANSYS analysis confirmed a significant decrease of helium channels cross-section caused by applied pressure. Also a new independent calculation of heat transfer confirmed the results presented in this paper.