Impedance Optimization And Measurements Of The Injection Stripline Kicker

Stripline kickers are commonly used for on-axis injection in the low emittance rings. The beam coupling impedances of the kickers normally show large contributions to the total impedance budget. In the High Energy Photon Source, the necessity of the short pulse bottom width (less than 10 ns) and strong deflection field requires the kicker to have a short length and a small gap between the electrodes, respectively. A new five-cell stripline kicker is proposed in order to save longitudinal space as well as to reduce the beam coupling impedance. Comprehensive studies have been undertaken to characterize the impedance of the stripline kicker. The beam coupling impedance and heat load dissipation on the kicker due to the beam passage are studied numerically. Strategies to further reduce the impedance are discussed. In addition, impedance bench measurements are launched to identify the impedance of the kicker experimentally. The longitudinal beam coupling impedance is measured with different terminations by using coaxial wire method. A satisfactory agreement has been reached between the numerical predictions and the measurements. A novel fasten block design with ceramic is proposed for the wire stretching and the center holding of the inner conductor in a small beam pipe.