Author: Vollinger, C.
Paper Title Page
SAPAG04 HOM-Mitigation for Future SPS 33-Cell 200 MHz Accelerating Structures 35
 
  • P. Kramer, C. Vollinger
    CERN, Geneva, Switzerland
  
  The CERN SPS 200 MHz trav­el­ling wave (TW) ac­cel­er­at­ing struc­tures pose an in­ten­sity lim­i­ta­tion for the planned High Lu­mi­nos­ity (HL-) LHC up­grade. Higher-or­der modes (HOMs) around 630 MHz have been iden­ti­fied as one of the main sources of lon­gi­tu­di­nal multi-bunch in­sta­bil­i­ties. Im­proved mit­i­ga­tion of these HOMs with re­spect to today’s HOM-damp­ing scheme is there­fore an es­sen­tial part of the LHC in­jec­tors up­grade (LIU) pro­ject. The basic prin­ci­ples of HOM-cou­plers in cav­i­ties and today’s damp­ing scheme are re­viewed, be­fore il­lus­trat­ing the nu­mer­ous re­quire­ments an im­proved damp­ing scheme for the fu­ture 33-cell struc­tures must ful­fil. These are, amongst oth­ers, the mit­i­ga­tion of HOMs sit­u­ated in the lower part of the struc­ture where there are no ac­cess ports for ex­trac­tion, a suf­fi­cient over­all damp­ing per­for­mance and an ac­cept­able in­flu­ence on the fun­da­men­tal ac­cel­er­at­ing pass­band (FPB). Dif­fer­ent ap­proaches tack­ling these chal­lenges are in­ves­ti­gated and their per­for­mance, ad­van­tages and pit­falls are eval­u­ated by ACE3P and CST elec­tro­mag­netic (EM) field solver suites.  
slides icon Slides SAPAG04 [2.184 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SAPAG04  
About • paper received ※ 19 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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