AVS 46th International Symposium
    Vacuum Technology Division Friday Sessions
       Session VT-FrM

Paper VT-FrM2
Vacuum Simulation of Linac Components to Optimize Pump Designs*

Friday, October 29, 1999, 8:40 am, Room 610

Session: Vacuum Systems, Design, and Engineering
Presenter: L.S. Tung, Lawrence Livermore National Laboratory
Authors: L.S. Tung, Lawrence Livermore National Laboratory
P. Shoaff, Lawrence Livermore National Laboratory
S. Shen, Lawrence Livermore National Laboratory
Correspondent: Click to Email
Methods have been developed to model the pressure history in linear accelerator components using Mathematica@footnote 1@ and Mathcad.@footnote 2@ The components are divided into sub-volumes represented as a lumped volume at a point in space. These sub-volumes are separated by conductances. The pressure distribution is obtained by solving the gas load equations for each sub-volume simultaneously for each time during pumpdown to the base pressure. Our models include the pressure dependence of speeds for all the system pumps as determined by a numerical fit to graphs provided by the vendor. Also included is the time-dependent outgassing history of oven-brazed copper based on recent rf cavity experiments and textbook data. Additionally, cryogenic pumping effects have been integrated into the modeling of the vacuum response in a superconducting linac structure. With these models, we can optimize the manifold design and pumping configurations. Our approach is especially useful for extrapolating costs for a large-scale linac. @FootnoteText@ *Work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48. @footnote 1@Mathematica software by Wolfram. @footnote 2@Mathcad software by Math Soft.