Author: Yang, M.-J.
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MOPOY011 Estimating the Transverse Impedance in the Fermilab Recycler 867
 
  • R. Ainsworth, P. Adamson, A.V. Burov, I. Kourbanis, M.-J. Yang
    Fermilab, Batavia, Illinois, USA
 
  Impedance could represent a limitation of running high intensity bunches in the Fermilab recycler. With high intensity upgrades foreseen, it is important to quantify the impedance. To do this, studies have been performed measuring the tune shift as a function of bunch intensity allowing the transverse impedance to be derived.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY011  
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TUPOR029 Study of Fast Instability in Fermilab Recycler 1728
 
  • S. A. Antipov
    University of Chicago, Chicago, Illinois, USA
  • P. Adamson, S. Nagaitsev, M.-J. Yang
    Fermilab, Batavia, Illinois, USA
 
  One of the factors which may limit the intensity in the Fermilab Recycler is a fast transverse instability. It develops within a hundred turns and, in certain conditions, may lead to a beam loss. Various peculiar features of the instability: its occurrence only above a certain intensity threshold, and only in horizontal plane, as well as the rate of the instability, suggest that its cause is electron cloud. We studied the phenomena by observing the dynamics of stable and unstable beam. We found that beam motion can be stabilized by a clearing bunch, which confirms the electron cloud nature of the instability. The findings suggest electron cloud trapping in Recycler combined function mag-nets. Bunch-by-bunch measurements of betatron tune show a tune shift towards the end of the bunch train and allow the estimation of the density of electron cloud and the rate of its build-up. The experimental results are in agreement with numerical simulations of electron cloud build-up and its interaction with the beam.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR029  
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