Keyword: ion-effects
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TUXA01 Advances in Understanding of Ion Effects in Electron Storage Rings simulation, emittance, storage-ring, injection 1267
 
  • J.R. Calvey, M. Borland, T.K. Clute, J.C. Dooling, L. Emery, J. Gagliano, J.E. Hoyt, P.S. Kallakuri
    ANL, Lemont, Illinois, USA
  
  Ion in­sta­bil­ity, in which beam mo­tion cou­ples with trapped ions in an ac­cel­er­a­tor, is a se­ri­ous con­cern for high-bright­ness elec­tron stor­age rings. For the APS-Up­grade, we plan to mit­i­gate co­her­ent ion in­sta­bil­ity using a com­pen­sated gap scheme. To study in­co­her­ent ef­fects (such as emit­tance growth), an ION­EF­FECTS el­e­ment has been in­cor­po­rated into the par­ti­cle track­ing code EL­E­GANT. The sim­u­la­tions in­clude mul­ti­ple ion­iza­tion, trans­verse im­ped­ance, and charge vari­a­tion be­tween bunches. Once these ef­fects are in­cluded, the sim­u­la­tions show good agree­ment with mea­sure­ments at the pre­sent APS. We have also in­stalled a gas in­jec­tion sys­tem, which cre­ates a con­trolled pres­sure bump of Ni­tro­gen gas in a short sec­tion of the APS ring. The re­sult­ing ion in­sta­bil­ity was stud­ied under a wide va­ri­ety of beam con­di­tions. For cases with no or in­suf­fi­cient train gaps, large emit­tance growth was ob­served. ION­EF­FECTS sim­u­la­tions of the gas in­jec­tion ex­per­i­ment and APS-U stor­age ring show the pos­si­bil­ity of run­away emit­tance blowup, where the blown-up beam traps more ions, dri­ving fur­ther in­sta­bil­ity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXA01  
About • paper received ※ 24 June 2021       paper accepted ※ 27 July 2021       issue date ※ 10 August 2021  
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