The Advanced Photon Source (APS) storage ring (SR) rf system employs four banks of four spherical, single-cell resonant cavities. Each cavity is tuned by varying the cavity volume through insertion/retraction of a copper piston located at the circumference of the cavity and oriented perpendicular to the accelerator beam. During the commissioning of the APS SR, the tuners and cavity tuner ports were prone to extensive arcing and overheating. The existing tuners were modified to eliminate the problems, and two new, redesigned tuners were installed. In both cases marked improvements were obtained in the tuner mechanical performance. As measured by tuner piston and flange surface temperatures, tuner heating has been reduced by a factor of five in the new version. Redesign considerations discussed include tuner piston-to-housing alignment, tuner piston and housing materials and cooling configurations, and tuner piston sliding electrical contacts. The tuner redesign is also distinguished by a modular, more maintainable assembly.
The Advanced Photon Source (APS) linac high-power switching system makes use of 340-size waveguide components. These components include vacuum-grade furnace-brazed transitions, pressurized-grade aluminum 340-size switches, and more recently 340-size ceramic windows. The fabrication of these 340-size windows proceeded with brazing of ceramic membrane to thin-walled copper sleeves and real-time network analyzer testing performed by the ASD (Accelerator Systems Division) RF (Radio Frequency) Group. Initially it was thought that this real-time testing of prototype hardware would be necessary in the investigative stage to establish the required dimensions and physical geometry to satisfy the 40-dB return-loss criteria. However, producing four windows now installed involved real-time network analyzer testing during production of each window conducted in parallel with adjustments of tuners designed into each 340-size ceramic window.
Date: October 10, 2002
Creator: Berg, S.; Bromberek, D.; Goeppner, G.; Haase, A.; Hoyt, J.; Michalek, W. et al.
The Advanced Photon Source Upgrade (APS-U) Project at Argonne will include generation of short-pulse x-rays based on Zholents deflecting cavity scheme. We have chosen superconducting (SC) cavities in order to have a continuous train of crabbed bunches and flexibility of operating modes. In collaboration with Jefferson Laboratory, we are prototyping and testing a number of single-cell deflecting cavities and associated auxiliary systems with promising initial results. In collaboration with Lawrence Berkeley National Laboratory, we are working to develop state-of-the-art timing, synchronization, and differential rf phase stability systems that are required for SPX. Collaboration with Advanced Computations Department at Stanford Linear Accelerator Center is looking into simulations of complex, multi-cavity geometries with lower- and higher-order modes waveguide dampers using ACE3P. This contribution provides the current R&D status of the SPX project.
Date: July 2012
Creator: Nassiri, A.; Berenc, T. G.; Borland, M.; Brajuskovic, B.; Bromberek, D. J.; Carwardine, J. et al.