Distribution Feedbox for the Superconducting Link (SCLink) and Magnets of HL-LHC

The High Luminosity LHC (HL-LHC) project aims at upgrading the LHC collider to increase its luminosity by about a factor of five. The electrical connection between the magnets in the LHC tunnel and the power converters in a new transverse tunnel will be supplied by a superconducting line (SCLink), consisting of ten MgB$_2$ cables housed into a 140 metre long flexible cryostat. This paper presents the detailed design for one of two types of distribution feedbox, (DFX) located between the magnet and the distribution feedbox. The vacuum barrier required to separate the vacuums of the upper SCLink and lower DFX sections; is to be integrated in the middle of the vertical section of DFX. A detailed study was performed, given the complexity of installing a vacuum barrier with a large diameter within a restricted height. Eccentric loading on the barrier is created by the “L-shape” vessel, necessary to accommodate the transition of the cable from vertical-to-horizontal. The solution considers a vacuum barrier assembly consisting of a flexible corrugated membrane (bellows) and deploys a lightweight “supporting cage” around the barrier and restraining rods in the horizontal section to ensure the barrier bares no substantial load or torque, and suffers no lateral or column type instability during operating and accidental conditions. The current design satisfies the mechanical and thermal design criteria outlined in the DFX specification.