Longitudinal Impedance Measurements and Simulations of a Three-Metal-strip Kicker

A kicker is a critical component for beam injection and accumulation in circular particle accelerators.A ceramic slat kicker plated with a TiN conductive coating was applied in the Beijing Electron Positron Collider(BEPCII).However,the ceramic slat kicker has experienced several sudden malfunctions during the operation of the BEPCII in the past.With a reliable kicker structure,a three-metal-strip kicker can substitute the original ceramic slat kicker to maintain the operational stability of the BEPCII.A comparison of the numerical simulation was conducted for three kicker models,demonstrating the comprehensive advantage of the three-metal-strip kicker.Furthermore,impedance bench measurements were conducted on a prototype of a three-metal-strip kicker.The longitudinal beam-coupling impedance was measured using a vector network analyzer via the coaxial wire method.A satisfactory agreement was obtained between the numerical simulations and measurements.Based on the numerical simulation data,the loss factor was 0.01721 V/pC,and the effective impedance was 3.59 mΩ(σ=10 mm).The simulation of the heat deposition on each part of the kicker demonstrated that 84.4％of the parasitic loss of the beam was deposited on the metal strips,and the total heat deposition power on the kicker was between 113.3 and 131.5 W.The obtained heat deposition powers can be considered as a reference for establishing the cooling system.