Author: Bradu, B.
Paper Title Page
TUXA03 Progress in Mastering Electron Clouds at the Large Hadron Collider 1273
 
  • G. Iadarola, B. Bradu, L. Mether, K. Paraschou, V. Petit, G. Rumolo, L. Sabato, G. Skripka, M. Taborelli, L.J. Tavian
    CERN, Geneva, Switzerland
  • K. Paraschou
    AUTH, Thessaloniki, Greece
  
  Dur­ing the sec­ond op­er­a­tional run of the Large Hadron Col­lider (LHC) a bunch spac­ing of 25 ns was used for the first time for lu­mi­nos­ity pro­duc­tion. With such a spac­ing, elec­tron cloud ef­fects are much more se­vere than with the 50-ns spac­ing, which had been used in the pre­vi­ous run. Beam-in­duced con­di­tion­ing of the beam cham­bers mit­i­gated the e-cloud for­ma­tion to an ex­tent that al­lowed an ef­fec­tive ex­ploita­tion of 25 ns beams. Nev­er­the­less, even after years of con­di­tion­ing, e-cloud ef­fects re­mained very vis­i­ble, af­fect­ing beam sta­bil­ity and beam qual­ity, and gen­er­at­ing strong heat loads on the beam screens of the su­per­con­duct­ing mag­nets with puz­zling fea­tures. In prepa­ra­tion for the High Lu­mi­nos­ity LHC up­grade, re­mark­able progress has been made in the mod­el­ing of the e-cloud for­ma­tion and of its in­flu­ence on beam sta­bil­ity, slow losses and emit­tance blow up, as well as in the un­der­stand­ing of the un­der­ly­ing be­hav­ior of the beam-cham­ber sur­face. In this con­tri­bu­tion, we de­scribe the main ex­per­i­men­tal ob­ser­va­tions from beam op­er­a­tion, the out­come of lab­o­ra­tory analy­sis con­ducted on beam screens ex­tracted after the run, and the main ad­vance­ments in the mod­el­ing of these phe­nom­ena.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXA03  
About • paper received ※ 19 May 2021       paper accepted ※ 12 July 2021       issue date ※ 29 August 2021  
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