High-temperature superconductor coating for coupling impedance reduction in the FCC-hh beam screen

The international Future Circular Collider study develops a conceptual design for a post Large Hadron Collider particle accelerator using 16 T superconducting dipoles for achieving p-p center-of-mass collision energies up to 100 TeV. One concern for this project is the beam coupling impedance especially at injection energy. A copper coated beam screen as in the LHC is planned, but preliminary studies indicate that copper at the high operating temperature of 50 K might not provide a sufficiently low impedance for a stable beam. In order to reduce the coupling impedance, we investigate high-temperature superconductors as a possible coating material in combination with copper as a hybrid system. The effect of different coating combinations are estimated through numerical calculations to identify the best hybrid beam screen coating system.