Analysis and Design of the Cryogenic System of the Future Circular Collider

Particle colliders are today's most advanced tools to perform particle physics experiments and penetrate the mysteries of matter. The largest existing particle collider, the LHC, is about to reach its technical limits and the particle physics society has to decide which future machine will enable the successful research to gain new knowledge. One option is the superconducting Future Circular Collider (FCC), which would exceed the LHC's size and generated particle energies by far. The enormous particle energies call for high magnetic fields, which only can be created reliably and economically by special superconducting materials at cryogenic temperature level. The intelligent design of the cryogenic distribution and discharge system to sustain the thermodynamic state of the superconducting electromagnets is the basis for an efficient and functional refrigeration and consequently for the physics experiments themselves. Several requirements and constraints limit the technical possibilities and the cryogenic system has to be designed to accomplish all the demands imposed by the original purpose to perform particle physics experiments. In the present thesis the development of a conceptual design for the FCC cryogenic distribution and discharge system is presented. Analytical and numerical methods are used to understand the cryogenic system's behaviour and to quantify the evolution and the magnitude of the thermodynamic state variables. The arrangement of the separately cooled units, the pipe diameters and the cryogen's initial states are varied and the different designs are exergetically analysed to obtain an indicatory value of the operational performance and costs. The respective capital costs and the availability as well as the compatibility with the optical lattice were taken into account to find a reliable and economic design meeting all requirements. For the final design an overall electrical power consumption of about 220 MW for the steady-state in nominal operation was calculated with an exergetic efficiency of 20 %. The results show that the construction and operation of the cryogenic distribution and discharge system for the FCC for sure is an ambitious, but possible endeavour

Investigation and performance assessment of hydraulic schemes for the beam screen cooling for the Future Circular Collider of hadron beams

The international study at CERN of a possible future circular collider (FCC) considers an option for a very high energy hadron-hadron collider located in a quasi-circular underground tunnel of about 100 km of length. The technical segmentation of the collider foresees continuously cooled sections of up to 10.4 km; throughout the entire section length, more than 600 kW of heat mainly generated by the beam synchrotron radiation must be removed from the beam screen circuits at a mean temperature of 50 K. The cryogenic system has to be designed to extract the heat load dependably with a high-efficiency refrigeration process. Reliable and efficient cooling of the FCC beam screen in all possible operational modes requires a solid basic design as well as well-matched components in the final arrangement. After illustrating the decision making process leading to the selection of an elementary hydraulic scheme, this paper presents preliminary conceptual designs of the FCC beam screen cooling system and compares the different schemes regarding the technical advantages and disadvantages with respect to the exergetic efficiency