| AVS 61st International Symposium & Exhibition | |
| Vacuum Technology | Wednesday Sessions |
| Session VT-WeA |
| Session: | Accelerator and Large Vacuum Systems II |
| Presenter: | Marcy Stutzman, Thomas Jefferson National Accelerator Facility |
| Authors: | M.L. Stutzman, Thomas Jefferson National Accelerator Facility P. Adderley, Thomas Jefferson National Accelerator Facility M.A. Mamun, Old Dominion University A.A. Elmustafa, Old Dominion University M. Poelker, Thomas Jefferson National Accelerator Facility |
| Correspondent: | Click to Email |
Long operational lifetime at the Jefferson Lab high polarization electron source requires vacuum approaching XHV (1x10-10 Pa). Determining the ultimate pressure in a chamber requires minimizing outgassing rate, maximizing pumping, and accurately measuring pressure. Two systems were used to study the ultimate pressure that could be achieved: test chambers that were fabricated to characterize the effects on outgassing of different chamber material processing and coatings, and a cryopumped electron source sized chamber. This paper presents both the characterization of XHV gauges and the ultimate pressure achieved in the various chambers. The extent to which temperature dependent outgassing rate can be exploited to improve ultimate pressure will also be discussed. Finally, progress on reconciling the persistent discrepancies between calculated and measured pressure will be presented.