rf deflector design of the CLIC test facility CTF3 delay loop and beam loading effect analysis

Beam injection and extraction in the delay loop of the CLIC Test Facility 3 (CTF3) for recombination of adjacent bunch trains, is performed by a specially designed rf deflector. A standing wave structure has been chosen for this purpose. Three possible solutions have been investigated, and a comparative analysis is presented. All of them satisfy the essential requirements of the system up to the maximum foreseen energy with the existing klystron. The final design of the rf deflector consists of two identical cavities connected to the rf power source through a hybrid junction that equally splits the power and isolates the klystron from reflections. The rf deflector design, the results of electromagnetic simulations, and the low level rf measurements are illustrated. The impact of beam loading in the rf deflectors on the transverse beam dynamics is also analyzed. The general expression of the single passage transverse wakefield is obtained and a dedicated tracking code has been written to study the multibunch multiturn effects. A complete analysis for different machine parameters and injection errors is presented and discussed. These numerical simulations indicate a tolerable beam emittance growth due to the transverse wakefield in the rf deflectors.