By Amalia Ballarino (CERN)

Each of the HL-LHC Cold Powering Systems incorporates, at its cold (4.5 K) end, a complex cryostat called a Distribution Feedbox (DF). Two types of DF cryostats are needed for the HL-LHC: five DFX, for the Triplets, and five DFM, for the Matching Sections. These cryostats will be located in the LHC underground tunnel at Points 1 and 5, in series with the magnets’ cryostats. They contain the saturated liquid helium bath where the MgB2 cables of the Superconducting Links (SC-Links) are interconnected to the Nb-Ti busbar going to the HL-LHC magnets.

The series construction of the DF cryostats takes place at the University of Southampton (SOTON) in the framework of the HL-LHC-UK2 contribution. Industry, Puma Engineering (UK), contributes via the University of Southampton.

Prior to UK2, and as part of the HL-LHC-UK1 contribution, the University of Southampton had already designed and manufactured a DFX cryostat that was successfully qualified at CERN in 2024 with the test of the first Cold Powering System.

In October 2024, SOTON completed production of the five DFX series units. This is the result of a collaborative effort between CERN, SOTON and industry, where strong commitment of each partner, together with an effective and trusting working spirit, brought us to the successful completion of the complex production. The DFM fabrication is on track for completion before the end of 2025.

Figure 2. DFX unit completed at SOTON.