RF design of normal conducting deflecting structures for the advanced photon source

Abstract

Use of normal conducting deflecting structures for production of short x-ray pulses is now under consideration at Argonne's Advanced Photon Source (APS). The structures have to produce up to 4 MV maximum deflection per pair of structures with a 1 kHz repetition rate. At the same time, the structures should not cause deterioration of beam properties in the APS ring. Following these requirements, we proposed 2815 MHz standing wave deflecting structures with heavy wakefield damping. In this paper we discuss design considerations and present our current design.

Coupled-bunch instability study of multi-cell deflecting mode cavities for the Advanced Photon Source

“…The cavities have high shunt impedance for the main deflecting mode and have naturally strong higher-order mode (HOM) shunt impedances, which will be damped [2]. HOM impedances have the tendency to create multibunch instabilities through a resonant effect with beam frequencies.…”

The wakefield effects of pulsed crab cavities at the Advanced Photon Source for short-x-ray pulse generation

“…As a near-term project, the APS has elected to pursue a pulsed system using room-temperature cavities [2]. The cavity design has been optimized to heavily damp parasitic modes while maintaining large shunt impedance for the deflecting dipole mode [3]. We evaluated a system consisting of three crab cavities as an impedance source and determined their effect on the single-and multi-bunch instabilities.…”

“…Progress made in the various aspects of the project are reported in these proceedings, which include the overall configuration of a pulsed crab-cavity system and its implementation in the APS storage ring [2], rf design of crab-cavity system [3], and multi-bunch instability analysis for the APS storage ring with crabcavity installed [4]. Here we describe the single-bunch instability caused by a crab-cavity system.…”