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Mapes, M.

Paper Title Page
RPPE046 A Summary and Status of the SNS Ring Vacuum Systems 2929
 
  • M. Mapes, H.-C. Hseuh, J. Rank, L. Smart, R.J. Todd, D. Weiss
    BNL, Upton, Long Island, New York
  • M.P. Hechler, P. Ladd
    ORNL, Oak Ridge, Tennessee
  
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

The Spallation Neutron Source (SNS) ring is designed to accumulate high intensity protons. The SNS ring vacuum system consists of the High Energy Beam Transport (HEBT) line, Accumulator Ring and the Ring to Target Beam Transport (RTBT) line. The Accumulator ring has a circumference of 248m with 4 arcs and 4 straight sections, while the RTBT and HEBT have a total length of 350m of beam transport line. Ultrahigh vacuum of 10-9 Torr is required in the accumulator ring to minimize beam-residual gas ionization. To reduce the secondary electron yield (SEY) and the associated electron cloud instability, the ring vacuum chambers are coated with Titanium-Nitride (TiN). This paper describes the design, fabrication, assembly and vacuum processing of the ring and beam transport vacuum systems as well as the associated instrumentation and controls.

 
RPPE047 Upgrade of RHIC Vacuum Systems for High Luminosity Operation 2977
 
  • H.-C. Hseuh, M. Mapes, L. Smart, R.J. Todd, D. Weiss
    BNL, Upton, Long Island, New York
  
  Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the U.S. Department of Energy.

With increasing ion beam intensity during recent RHIC operations, pressure rises of several decades were observed at most room temperature sections and at a few cold sections. The pressure rises are associated with electron multi-pacting, electron stimulated desorption and beam ion induced desorption and have been one of the major intensity and luminosity limiting factors for RHIC. Improvement of the warm sections has been carried out in the last few years. Extensive in-situ bakes, additional UHV pumping, anti-grazing ridges and beam tube solenoids have been implemented. Several hundred meters of NEG coated beam pipes have been installed and activated. Vacuum monitoring and interlock were enhanced to reduce premature beam aborts. Preliminary measures, such as pumping before cool down to reduce monolayer condensates, were also taken to suppress the pressure rises in the cold sections. The effectiveness of these measures in reducing the pressure rises during machine studies and during physics runs are discussed and summarized.