Measurement scheme of kicker impedances via beam-induced voltages of coaxial cables

A new theory, which satisfies the causality condition, is developed to describe impedances of kicker magnets with coaxial cables. The theoretical results well describe measurement results, which are obtained by standard wire methods. On the other hand, when beams pass through the kicker, voltages are induced at the terminals of coaxial cables. In other words, by analyzing the voltages, the kicker impedance for the beams can be obtained. The observed impedances are consistent with the theoretical results. The theory describes the impedance for non-relativistic beams, as well. The theoretical, simulation and measurement results indicate that the horizontal kicker impedance is drastically reduced by the non-relativistic effect.

► We develop an innovative method to measure kicker impedance including power cable.
► By analyzing voltages at the ends of coaxial cables, the impedance is derived.
► The horizontal impedance is reduced as the beam becomes non-relativistic.