ANL, Argonne, Illinois, USA
The final design phase is underway for the APS-Upgrade project's storage ring vacuum system. Many aspects of the design are being worked on to address challenging interfaces and to optimize vacuum system performance. Examples of recent work include updates to ray tracing and vacuum analysis, new developments in vacuum chamber and photon absorber design, and further refinement of vacuum pumping plans to achieve the best possible pressure distributions. Recent R&D work and results from a vacuum system sector mockup have also informed designs and installation plans. An overview of progress in these areas and remaining challenges is pre-sented.
ANL, Argonne, Illinois, USA
The APS-Upgrade project will build a diffraction lim-ited storage ring requiring a vacuum system design with small aperture vacuum chambers passing through narrow magnet poles. The small apertures dictate that the walls of the vacuum chambers act as distributed photon ab-sorbers. The vacuum chambers must be designed robustly so a thorough understanding of the synchrotron ray trac-ing with beam missteering is required. A MatLab program has been developed to investigate 3D ray tracing with beam missteering. The program dis-cretizes local phase spaces of deviation possibilities along the beam path in both the horizontal and vertical planes of motion and then projects rays within a 3D mod-el of the vacuum system. The 3D model contains ele-ments in sequence along the beam path which represent both chamber segments and photon absorbers. Ray strikes are evaluated for multiple worst-case criteria such as local power intensity or strike offset from cooling channels. The worst case results are plotted and used as boundary conditions for vacuum chamber ther-mal/structural analyses. The results have also helped inform decisions about practical beam position limits.
