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Macdonald, B. F.

Paper Title Page
WEPC007 Vacuum Performance of the Diamond Light Source In-vacuum Insertion Devices 1995
 
  • M. P. Cox, S. Bryan, B. F. Macdonald, H. S. Shiers
    Diamond, Oxfordshire
 
  Diamond Light Source is the UK's new 3 GeV 3rd generation synchrotron light source with a 562 m circumference electron storage ring. At the start of user operations in January 2007, 5 in-vacuum undulators were in operation and a further 3 units have been installed subsequently. This paper describes the vacuum performance of these devices. 3 different mechanical configurations with different undulator canting angle and different pumping arrangements of the interconnecting vessels are installed. One configuration has non-evaporable getter (NEG) coated interconnecting vessels. Vacuum simulations were carried out on these configurations as part of the vacuum design process to predict their performance. Following final magnetic characterization, each of the devices was vacuum assembled and baked ex-situ for an extended period and then installed under dry nitrogen purge conditions, eliminating the need for a time-consuming in-situ bakeout in most cases. After a period of pump down and beam conditioning, the operating pressures in all the in-vacuum undulators were below the target specification and produced acceptably low Gas Bremsstrahlung radiation levels in the beamlines.