Functional analysis and design of the cryogenic system for the HL-LHC IT String test bench at CERN

The High Luminosity LHC (HL-LHC) is a project aiming to upgrade the LHC collider to maintain scientific progress and exploit its full capacity. In the HL-LHC configuration, the Inner Triplet (IT) magnets of the present LHC will be replaced by a new set of higher performance magnets. The collective behaviour of the new magnets and the related systems will be studied and validated in a dedicated cryogenic test facility, the IT String, currently under construction. This paper presents the results of the functional analysis performed to design the cryogenic system for the IT String. The required operation modes are identified and detailed together with the operational parameters and constraints used to define the cryogenic system. The layout of the cryogenic distribution system that fulfils the requirements of the IT String is presented and the characteristics of the main components are described.