Detailed study of the cryogenic jumper connections between the cryogenic distribution line and the superconducting magnets of the High Luminosity LHC upgrade at CERN

Abstract The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) project will require a new cryogenic system to cool the new superconducting components in the final focusing regions for the ATLAS and the CMS experiments. New superconducting magnets operating in pressurized HeII at 1.9 K will replace the existing ones and each magnet will generate heat loads of several hundred watts. The liquid and gaseous helium needed for the magnets will be supplied by new multi-header cryogenic distribution lines (QXL). The connections between the magnets and the QXL are performed at specific service modules via cryogenic jumpers, which must provide high flexibility while being compatible with the limited space in the LHC tunnel. This article describes the development of the QXL jumpers and presents their final configuration. It covers the mechanical and thermal-hydraulic validation, including a test campaign carried out to characterize the bending stiffness of the metallic flexible hoses used for cryogenic lines.