Author: Kourbanis, I.
Paper Title Page
THO4LR04 Fast Transverse Instability and Electron Cloud Measurements in Fermilab Recycler 419
 
  • J.S. Eldred, P. Adamson, D. Capista, N. Eddy, I. Kourbanis, D.K. Morris, J.C.T. Thangaraj, M.-J. Yang, R.M. Zwaska
    Fermilab, Batavia, Illinois, USA
  • J.S. Eldred
    Indiana University, Bloomington, Indiana, USA
  • Y. Ji
    IIT, Chicago, Illinois, USA
  
  A new trans­verse in­sta­bil­ity is ob­served that may limit the pro­ton in­ten­sity in the Fer­mi­lab Re­cy­cler. The in­sta­bil­ity is fast, lead­ing to a beam-abort loss within two hun­dred turns. The in­sta­bil­ity pri­mar­ily af­fects the first high-in­ten­sity batch from the Fer­mi­lab Booster in each Re­cy­cler cycle. This paper an­a­lyzes the dy­nam­i­cal fea­tures of the desta­bi­lized beam. The in­sta­bil­ity ex­cites a hor­i­zon­tal be­ta­tron os­cil­la­tion which cou­ples into the ver­ti­cal mo­tion and also causes trans­verse emit­tance growth. This paper de­scribes the fea­si­bil­ity of elec­tron cloud as the mech­a­nism for this in­sta­bil­ity and pre­sents the first mea­sure­ments of the elec­tron cloud in the Fer­mi­lab Re­cy­cler. Di­rect mea­sure­ments of the elec­tron cloud are made using a re­tard­ing field an­a­lyzer (RFA) newly in­stalled in the Fer­mi­lab Re­cy­cler. In­di­rect mea­sure­ments of the elec­tron cloud are made by prop­a­gat­ing a mi­crowave car­rier sig­nal through the beampipe and an­a­lyz­ing the phase mod­u­la­tion of the sig­nal. The max­i­mum be­ta­tron am­pli­tude growth and the max­i­mum elec­tron cloud sig­nal occur dur­ing min­i­mums of the bunch length os­cil­la­tion.  
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