Status of Rf Deflecting Cavity Design for the Generation of Short X-ray Pulses in the Advanced Photon Source Storage Ring

The Advanced Photon Source (APS) at Argonne National Laboratory is exploring the possibility of using radio frequency deflection to generate x-ray radiation pulses on the order of 1 pico-second (Delta t – 70%) or less [1]. This scheme is based on a proposal by A. Zholents et al. [2] that relies on manipulating the transverse momentum of the electrons in a bunch by using an rf deflecting cavity to induce a longitudinally dependent vertical deflection of the beam. The beam will then travel through a number of undulators before arriving at a second set of deflecting cavities where the deflection is reversed such that the remainder of the storage ring is largely unperturbed [3]. Considerable effort has been expended on the design of a superconducting rf deflecting cavity operating in the Sband at 2.8 GHz to address fundamental design issues including cavity geometry, deflecting voltage, rf power coupling, tuning, and damping of higher-order and lowerorder modes. In this paper we present simulation results and analysis of an optimized superconducting rf deflecting cavity design for the APS storage ring.