Optimized injector schemes for FCC-ee positron production

Injectors and in particular the positron production systems are a crucial element linear circular colliders. The proposed FCC-ee injector linac accelerates both electrons positrons up to 6 GeV order be injected into Pre-Booster Ring (PBR) with high intensity of 3.5 nC per bunch for Z running mode. current design baseline is based on SuperKEKB scheme, which electron beams share same linacs fixed target configuration on-axis hole beam passage. One main drawbacks this scheme efficiency at exit linac. In achieve better performance higher yield, paper we study different bypass injection options. Start-to-end optimization production, acceleration transport from feeding source damping ring also being presented.