Abstract
Experimental observations on the electron cloud have been collected at the CERN Proton Synchrotron machine throughout the last two years. At the same time, an intense campaign of simulations has been carried out to understand the observed electron cloud buildup and the related instability. In this paper, the results of the numerical simulations are presented and discussed.
Highlights
Gas ionization and electron multiplication due to the secondary-emission process on the inner side of the beam pipe may induce the buildup of an electron cloud, which can significantly degrade the performance of rings operating with closely spaced proton or positron bunches
In the case of the CERN Proton Synchrotron (PS) machine, the electron cloud has been observed since the year 2000 for LHC-type bunch trains, i.e., 72 bunches of Nb 11 1010 protons per bunch (p=b) spaced by 25 ns
For all the cases that we have examined in this study, the rise time of the instability is shorter in the vertical plane, and the related vertical emittance increase over 2000 turns is always significantly larger
Summary
Gas ionization and electron multiplication due to the secondary-emission process on the inner side of the beam pipe may induce the buildup of an electron cloud, which can significantly degrade the performance of rings operating with closely spaced proton or positron bunches. [3] describes further details of the applied beam manipulations as well as the PS beam observations with an electron cloud) Under these conditions, data could be recorded concerning the buildup process, and the induced instability [3]. The two codes developed at CERN, ECLOUD and HEADTAIL [4], can simulate both the buildup process of the electron cloud and its expected effect on the single bunch that passes through it [1,5,6,7].
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