LLL 100-MeV Electron Linac: Design Considerations and Performance of the Beam-Transport Vacuum System

This paper describes the vacuum system for the beam-transport lines used with the Lawrence Livermore Laboratory 100-MeV electron-positron linear accelerator. It is operated in the high (10-4 to 10-5 Pa) range using standard ion pumps with turbomolecular pumps for roughdown. This paper also reviews the important factors considered during the initial design phases; these factors have contributed to the very reliable performance of the vacuum system since its startup five years ago. The cleaning and handling procedures used on the beam-transport lines, magnet vacuum chambers, and other vacuum components are discussed.