AVS 58th Annual International Symposium and Exhibition
    Vacuum Technology Division Tuesday Sessions
       Session VT-TuP

Paper VT-TuP6
Combination of NEG and Sputter-Ion Pumps for Particle Accelerator Vacuum Systems

Tuesday, November 1, 2011, 6:00 pm, Room East Exhibit Hall

Session: Vacuum Technology Poster Session & Student Poster Competition
Presenter: Paolo Manini, SAES Getters
Authors: P. Chiggiato, CERN, Switzerland
J.M. Jimenez, CERN, Switzerland
S. Meunier, CERN, Switzerland
I. Wevers, CERN, Switzerland
A. Bonucci, SAES Getters
A. Conte, SAES Getters
P. Manini, SAES Getters
Correspondent: Click to Email
NEG and sputter-ion pumps are usually combined in particle accelerators to attain UHV pressure specifications. NEG pumps provide very high pumping speed at a reasonable cost for most of the residual gases except CH4 and rare gases, which amount to less than an hundredth of the total outgassing rate. Sputter-ion pumps remove all gases, though with a lower pumping speed. As a consequence, an optimized design should be based on NEG assisted by sputter-ion pumps for the gases that are not adsorbed chemically. Two examples of such configuration are here described. In the first, a commercial NEG lump pump is installed on a dedicated set-up together with sputter-ion pumps of different nominal pumping speeds. We show that the ultimate pressure achieved in the system does not depend on the applied sputter-ion pump nominal pumping speed in the range 30 to 400 ls-1, and that values in the XHV range can be reached. In the second, we consider the vacuum system of the long straight section of the Large Hadron Collider (LHC) where most of the vacuum pipes were coated by magnetron sputtering with thin Ti-Zr-V films using Kr as discharge gas; the guidelines for the choice of the location and quantity of the sputter-ion pumps are reviewed in term of sectorization criteria and CH4 and Kr outgassing rates.