Longitudinal impedance of a prototype kicker magnet system

The longitudinal impedance of a kicker magnet system for the proposed KAON factory has been measured from 0.3 to 200 MHz. The measurement was done by transforming the kicker magnet under test into a coaxial line in order to measure the transmission parameter S₂₁ through the line. The measurement was performed in two frequency ranges. From 0.3 to 50 MHz the magnet was transformed into a 50 Ω coaxial line, and from 45 to 200 MHz into a 180 Ω coaxial line. Resonances in the longitudinal impedance spectrum are due to the electrical resonant modes of the kicker magnet system. The effect on the longitudinal impedance of a speed-up network and a saturating inductor, installed on the input to the kicker magnet to improve its kick performance, was determined. The speed-up network can damp some of the resonances whereas the saturating inductor can eliminate the resonances due to the input cable of the kicker magnet. Above 45 MHz where attenuation in the LC cells of the kicker magnet is strong, external components connected to the kicker magnet have negligible influence on the longitudinal impedance. Hence the longitudinal impedance spectrum of the kicker magnet in the 45 to 200 MHz frequency range does not depend on external components such as the speed-up network, the saturating inductor and the input and output cables