A two-frequency RF cavity for the PSI-XFEL: Design and beam dynamics simulations

The RF design of the two-cell cavity and the coupling schemes for both frequencies are presented. Mode separation, which ensures adequate operation, is achieved by profiling the cavity walls. The flexibility of such a design to shape the longitudinal phase space is illustrated with beam dynamics simulations. The transverse emittance is shown to be nearly unchanged by combining emittance compensation and a beam matching scheme. The deleterious effects of the transverse RF fields are consequently reduced to a minimum.