Refrigeration assessment of the existing cryogenic plants for the high luminosity upgrade of the Large Hadron Collider (LHC)

The cryogenic system of the LHC will be upgraded by 2025 to comply with a considerable increase of beam induced heat loads deriving from higher beam currents and peak luminosity levels from the High Luminosity LHC. The current baseline foresees a modified sectorisation scheme with three additional cryogenic plants dedicated to cool the insertions at LHC's points 1, 4 and 5, reducing the refrigeration duty of the existent adjacent plants. This paper assesses the refrigeration duty of the eight existing plants considering the modified sectorisation and increased heat load deposition. The accelerator loads and distribution losses are quantified for each plant and compared to the existing refrigeration capacity. The heat load values were obtained from the extrapolation of previous LHC assessments as well as from new calculations. Specifically for the LHC point 4 cryogenic equipment, based on updated refrigeration requirements, the upgrade of an existing plant is proposed as an alternative to the baseline scenario.