Longitudinal impedances of some simplified ferrite kicker magnet models

Two simplified models are presented in this paper in order to estimate the contribution of fast kicker magnets to the longitudinal impedance of synchrotrons. The first model is cylindrically symmetric with ferrite surrounding the beam aperture. The beam aperture is rectangular in the second model. Two opposing sides consist of ferrite and the others consist of perfect conductors. The analytical expressions of the longitudinal impedance for the two models are first derived. Subsequently a numerical comparison between these expressions and simulation results obtained with the code HFSS are presented.