ANL, Argonne, Illinois
The Advanced Photon Source (APS) at Argonne National Laboratory is exploring the idea of using radio frequency deflection to generate x-ray radiation pulses on the order of 1 pico-second or less [1]. This scheme is based on that first proposed by A. Zholents et al. [2], and relies on manipulating the transverse momenta of the electrons in the bunch. An rf deflecting cavity is used to induce a longitudinally dependent vertical angular deflection to the beam. The beam propagates through a number of undulators, and a second rf deflecting cavity downstream cancels the first cavity effect such that the rest of the storage ring is unperturbed. A critical criteria is that the emittance blowup induced by nonlinearities and uncompensated chromaticity be corrected, and a sextupole optimization scheme has been shown to be feasible [3,4]. Considerable effort has been carried out on the design of a superconducting (SC) rf deflecting cavity operating in the S-Band (2.8 GHz) to address fundamental design issues including rf error tolerances [4], cavity geometry, deflecting voltage, rf power coupling, tuning, distribution, and damping of higher order and lower order modes (HOM, LOM). The project status is described.
[1] K. Harkay, et al. Proc. 2005 PAC, 668.
[2] A. Zholents, et al. NIM A425, 385 (1999).
[3] M. Borland, V. Sajaev, Proc. 2005 PAC, 3886.
[4] M. Borland, PRST-AB 8, 074001 (2005).
