| AVS 65th International Symposium & Exhibition | |
| Vacuum Technology Division | Tuesday Sessions |
| Session VT-TuM |
| Session: | Large Vacuum Systems and Accelerator Vacuum Technology |
| Presenter: | Yulin Li, Cornell University |
| Authors: | X. Liu, Cornell University D.C. Burke, Cornell University A.T. Holic, Cornell University Y. Li, Cornell University A. Lyndaker, Cornell University |
| Correspondent: | Click to Email |
A sextant of Cornell Electron Storage Ring (CESR) is currently being upgraded with Double Bend Achromat (DBA) lattice and CHESS Compact Undulators (CCUs) in order to significantly boost the performance of Cornell High Energy Synchrotron Source (CHESS). With this upgrade, dubbed CHESS-U, CESR is converted from a counter-propagating two-beam ring to a single-beam ring, and the beam energy will be increased from 5.3 GeV to 6 GeV. The beam current for normal operation will also be increased, from 120 mA to 200 mA. The beampipe aperture of this new section is much smaller than the rest of CESR, and therefore the beam pipes and vacuum pumping are quite different from the rest of CESR too.
The beam pipes are mainly made of three types of aluminum extrusions, fitting inside quadrupole magnets, dipole magnets, and undulators respectively. The dipole extrusion includes an ante-chamber for distributed pumping using NEG strips (SAES St 707). An exception is the dipole chamber from which the undulator X-ray beam exits. This chamber is instead made of two machined halves that are welded together.
In this presentation, we will give a brief overview of the design of the vacuum system, and then show some important details in chamber production and installation, such as extrusion bending by stretch forming, chamber welding and distortions, NEG strip pumping, etc. Base vacuum performance will be reported as well. Details regarding the crotch absorber will be reported in a separate presentation.