Abstract
There are 35 straight sections in the APS-U storage ring that contain either Hybrid Permanent Magnet Undulators (HPMU), an Intermediate Energy X-ray (IEX) device, or Superconducting Undulators (SCU). Two unique vacuum systems were designed to provide ultra-high vacuum (UHV) continuity between storage ring (SR) sectors across these straight sections. The Insertion Device Vacuum Chamber (IDVC), nominally 5.363 meters long, requires bake-out before operation and expands 10mm on both ends. The IDVC operates with a 600 micron thick wall over a length of 5050 mm and requires the use of 1 ion pump and 7 NEG cartridges for pumping down the system to UHV levels. Transitions from the storage ring aperture to the IDVC elliptical aperture are machined into the ends of the IDVC so that the material continuity is maximized across the length of the chamber. A discrete compact photon absorber located in the downstream end of the chamber protects the downstream end of the IDVC and 1.2 meters of downstream vacuum equipment. The SCU vacuum system is comprised of 3 discrete vacuum chambers and is nominally 5.383 meters long. The vacuum system spanning the 4.8 meter long cryostat operates with a 400 micron minimum wall thickness at a temperature of 20K. Outside the cryostat on the up and downstream end of the straight reside the “warm” chambers. These chambers protect the SCU and downstream vacuum equipment, respectively, from upstream B:M1 radiation via machined inline absorbers. They also provide UHV continuity between the storage ring vacuum system and the SCU cryostat. Both vacuum systems require the ability to align the beam aperture centers to ±50 microns along their lengths.