The Planning of the Cryogenic Supply Infrastructure for the Superconducting Cavities of the European XFEL Linear Accelerator

A 1.7 km long pulsed, superconducting linear accelerator is planned to deliver electrons at energies up to 20 GeV for the European X‐ray Free Electron Laser, ‘European X‐FEL’. The 3.4 km long accelerator/X‐FEL system starts at the DESY site with two parallel injector sections and a booster section in line with the rest of the linac. The linac will consist of about 120 cryomodules each containing a quadrupole magnet package and eight 9‐cell niobium cavities operated at 1.3 GHz in a helium bath at 2 K and at shield temperatures around 6 K and 60 K. As part of the preparation phase for the start of the civil engineering (“plan approval procedure”) the pre‐planning of the tunnel layout, of all underground shafts, buildings and necessary infrastructure was completed. The planning of the cryogenic supply infrastructure for the XFEL linac is presented.