Spallation Neutron Source ring vacuum systems

The Spallation Neutron Source ring, which is presently being commissioned at Oak Ridge National Laboratory, is designed to accumulate high-intensity protons. Ultrahigh vacuum of 10(-9) torr is required in the accumulator ring to minimize beam-residual gas ionization. To reduce the secondary-electron yield and the associated electron cloud instability, the ring vacuum chambers are coated with titanium nitride (TiN). In order to minimize radiation exposure, quick-disconnect chain clamp flanges are used in some areas where radiation levels are expected to be high. This article describes the design, fabrication, assembly, and vacuum processing of the ring and beam transport vacuum systems, as well as the associated vacuum instrumentation. (c) 2006 American Vacuum Society.