Vacuum System Requirements for a Higgs Factory $e^+e^−$ Collider

Future e⁺e^{−} Higgs Factories (HF) are challenging machines which require a careful design of their vacuum systems. The high-energy of the beams implies a very high critical energy of the synchrotron radiation (SR) spectrum, and a large SR power. From the point of view of the linear SR power density and flux, HFs are not as extreme as some existing SR light sources, for which cooling and pumping solutions have been conceived and validated. The main problem with HFs is their sheer size, which calls for a standardization of the design for the long, repetitive arc sections, with a need to find a "cheap" solution which could be transfered easily to industry. This paper will compare the merits of different pumping solutions, and choice of materials for the vacuum chambers.