First Cavity Design Studies for the BESSY-VSR Upgrade Proposal

Recently HZB proposed an upgrade of the 3 rd generation synchrotron light source BESSY II allowing simultaneous long and short pulse operation [1]. For this scheme superconducting higher harmonic cavities of the fundamental 500 MHz at two frequencies need to be installed in the BESSY II storage ring. Given an appropriate choice of the higher harmonics the resulting gradient leads to a beating