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Wei, J.

Paper Title Page
TUXAB02 E-cloud experiments and cures at RHIC 759
  • W. Fischer, M. Blaskiewicz, J. M. Brennan, H.-C. Hseuh, H. Huang, V. Ptitsyn, T. Roser, P. Thieberger, D. Trbojevic, J. Wei, S. Y. Zhang
    BNL, Upton, Long Island, New York
  • U. Iriso
    ALBA, Bellaterra (Cerdanyola del Valles)
  Funding: Work supported by U. S. DOE under contract No DE-AC02-98CH1-886.

Since 2001 RHIC has experienced electron cloud effects, which have limited the beam intensity. These include dynamic pressure rises – including pressure instabilities, a reduction of the stability threshold for bunches crossing the transition energy, and possibly slow emittance growth. We report on the main observations in operation and dedicated experiments, as well as the effect of various countermeasures including baking, NEG coated warm pipes, pre-pumped cold pipes, bunch patterns, scrubbing, and anti-grazing rings.

slides icon Slides  
FRPMS081 Geometric Effects on Electron Cloud 4243
  • L. Wang, A. Chao
    SLAC, Menlo Park, California
  • J. Wei
    BNL, Upton, Long Island, New York
  The development of an electron cloud in the vacuum chambers of high intensity positron and proton storage rings may limit the machine performances by inducing beam instabilities, beam emittance increase, beam loss, vacuum pressure increases and increased heat load on the vacuum chamber wall. The electron multipacting is a kind of geometric resonance phenomenon and thus is sensitive to the geometric parameters such as the aperture of the beam pipe, beam shape and beam bunch fill pattern, etc. This paper discusses the geometric effects on the electron cloud build-up in a beam chamber and examples are given for different beams and accelerators.