Design of a high-current injector and transport optics for the ilc electron source

A train of 1.3-ns micro bunches of longitudinally polarized electrons are generated in a 140-kV DC-gun based injector in the International Linear Collider electron source; a bunching system with extremely high bunching efficiency to compress the micro-bunch down to 20 ps FWHM is designed. Complete optics to transport the electron bunch to the entrance of the 5-GeV damping ring injection line is developed. Start-to-end multi-particle tracking through the beamline is performed including the bunching system, pre-acceleration, vertical chicane, 5- GeV superconducting booster linac, spin rotators and energy compressor. With optimizations of energy compression, 94% of the electrons from the DC-gun are captured within the damping ring 6-D acceptance - A_x + A_y les 0.09 m and DeltaEtimesDeltaz les (plusmn25 MeV) times (plusmn3.46 cm) - at the entrance of the damping ring injection line.