Measurements of the electron cloud in the APS storage ring.

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Synchrotron radiation interacting with the vacuum chamber walls in a storage ring produce photoelectrons that can be accelerated by the beam, acquiring sufficient energy to produce secondary electrons in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, as is the case with the aluminum chambers in the Advanced Photon Source (APS) storage ring, a runaway condition can develop. As the electron cloud builds up along a train of stored positron or electron bunches, the possibility exists that a transverse perturbation of the head bunch will be communicated to trailing bunches ... continued below

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5 p.

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Harkey, K. C. April 16, 1999.

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Description

Synchrotron radiation interacting with the vacuum chamber walls in a storage ring produce photoelectrons that can be accelerated by the beam, acquiring sufficient energy to produce secondary electrons in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, as is the case with the aluminum chambers in the Advanced Photon Source (APS) storage ring, a runaway condition can develop. As the electron cloud builds up along a train of stored positron or electron bunches, the possibility exists that a transverse perturbation of the head bunch will be communicated to trailing bunches due to interaction with the cloud. In order to characterize the electron cloud, a special vacuum chamber was built and inserted into the ring. The chamber contains 10 rudimentary electron-energy analyzers, as well as three targets coated with different materials. Measurements show that the intensity and electron energy distribution are highly dependent on the temporal spacing between adjacent bunches and the amount of current contained in each bunch. Furthermore, measurements using the different targets are consistent with what would be expected based on the SEY of the coatings. Data for both positron and electron beams are presented.

Physical Description

5 p.

Notes

INIS; OSTI as DE00011127

Medium: P; Size: 5 pages

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  • 1999 Particle Accelerator Conference (PAC '99), New York, NY (US), 03/29/1999--04/02/1999

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  • Report No.: ANL/ASD/CP-97721
  • Grant Number: W-31109-ENG-38
  • Office of Scientific & Technical Information Report Number: 11127
  • Archival Resource Key: ark:/67531/metadc618815

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  • April 16, 1999

Added to The UNT Digital Library

  • June 16, 2015, 7:43 a.m.

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  • April 11, 2017, 12:42 p.m.

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Harkey, K. C. Measurements of the electron cloud in the APS storage ring., article, April 16, 1999; Illinois. (digital.library.unt.edu/ark:/67531/metadc618815/: accessed September 19, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.