HOM test of the storage ring single-cell cavity with a 20-MeV e(sup minus) beam for the Advanced Photon Source (APS).

摘要

To test the effectiveness of damping techniques of the APS storage ring single-cell cavity, a beamline has been designed and assembled to use the ANL Chemistry Division linac beam (20-MeV, FWHM of 20 ps). A single-cell cavity will be excited by the electron beam to investigate the effect on higher-order modes (HOMs) with and without coaxial dampers (H-loop damper, E-probe damper), and wideband aperture dampers. In order for the beam to propagate on- and off-center of the cavity, the beamline consists of two sections -- a beam collimating section and a cavity measurement section -- separated by two double Aluminum foil windows. RF cavity measurements were made with coupling loops and E-probes. The results are compared with both the TBCI calculations and 'cold' measurements with the bead-perturbation method. The data acquisition system and beam diagnostics will be described in a separate paper.