Speakers
Description
In the framework of the Future Circular Collider (FCC) study at CERN, a conceptual design of a cooling scheme for Nb$_3$Sn-based accelerator magnets operating at 4.5 K is proposed for the FCC-hh configuration. This alternative, at a higher operating temperature than the baseline at 1.9 K using Helium II, is driven by the efforts towards a more energetically sustainable machine, while ensuring compatibility with the tunnel structure envisaged for the FCC-ee configuration, and providing a technically viable solution for the required superconducting magnets.
The study is carried out for the latest configuration of the FCC-hh machine (F14 scenario), considering Nb$_3$Sn superconducting magnets with an operational magnetic field of 14 T, for a centre-of-mass energy of 84 TeV with a magnetic filling scheme of 83%. The updated heat loads are presented, and the system parameters, along with longitudinal and expected radial temperature gradients in the magnet structure, are evaluated. The move from 1.9 K, operation making extensive use of Helium II, towards 4.5 K using single-phase helium significantly reduces the overall cryogenic power consumption by at least 30%, and the machine's helium inventory by 50% with respect to the baseline scenario at 1.9 K. Other advantages, such as a simplification of the cold mass structure and the relaxation of access exclusion zones due do the more manageable helium content in case of release are analyzed and compiled. The challenges associated with this cryogenic cooling scheme, which has so far not been implemented in such a large-scale accelerator, are addressed.
