Impact of the Number of dpa on the Superconducting Properties in HiLumi-LHC and FCC Accelerators

The aim of this paper is to estimate the change of the superconducting properties Tc, Jc, and Bc2 in the quadrupoles of the future accelerators HiLumi-LHC and FCC, submitted to irradiation by multiple high-energy sources. The estimations are performed based on the number of displacements per atom (dpa), calculated by means of the FLUKA code. It is found that the dpa can be used as a single parameter for describing the radiation induced change of Tc, the degree of atomic order parameter S, and the lattice parameter a in the case of multiple energy sources. The mechanism leading to the enhancement of $J_{\text{c}}$ after proton and neutron irradiation is analyzed based on a possible correlation with the concentration of Frenkel defects produced by the irradiation. Experimental data on Jc/Jco versus dpa at 4.2 K allow estimating Jc in the quadrupoles of HiLumi-LHC and FCC/Run1, where the values of dpa for lifetime are 2.5 × 10−4 and 5 × 10−4, respectively. The dpa in FCC/Run2 is much higher, 3 × 10 −3, thus reaching well beyond the maximum of Jc versus dpa. An accurate estimation of the variation of Tc, Jc, and B c2 is performed based on earlier irradiation data with 14-MeV neutrons.