By Carmen Abad Cabrera (CERN)

In November 2024, the D1-DFX Connection Module (DCM) cryostat prototype assembly was successfully completed and validated with a final pressure test.

The DCM cryostat, part of HL-LHC Work Package 3 (Magnets), ensures electrical continuity between the conductors from the DFX end of the cold powering system to the D1 magnet. It houses the Lambda Plate, a hydraulic barrier that separates regions of superfluid helium (1.9 K) and normal liquid helium (4.5 K). The Lambda Plate incorporates the Nb-Ti busbar extending into the DFX and provides a high-pressure (20 bar) barrier against the pressurized helium volume of the Work Package 6a Cold Powering System. Additionally, the DCM contains a bypass diode stack and ensures the required environmental operating conditions for its components.

At the start of 2024, a blank assembly of the main vessels was performed to validate the assembly procedure for the final prototype. The DCM prototype assembly subsequently began as a collaborative effort between the TE-MSC-LMF team, responsible for the conductors and splices within the module, and the TE-MSC-CMI team, who carried out the mechanical assembly. The vacuum vessel and thermal shields were supplied by external companies, the helium vessel was manufactured by EN-MME, and the diode stack was provided by TE-MPE. During the assembly process, several CERN groups collaborated, with EN-MME handling welding and weld inspections, TE-VSC conducting leak and pressure tests, and BE-GM performing mechanical measurements.

With this final validation, the DCM prototype assembly is now ready to be installed into the IT String.