Keyword: HOM
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WEPSB09 Comparision of Higher Order Modes Damping Techniques for Array of Single Cell Cavities impedance, damping, extraction, higher-order-mode 174
 
  • Ya.V. Shashkov, N.P. Sobenin
    MEPhI, Moscow, Russia
  • M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  
  Funding: Research supported by RFBR grant 13-02-00562/14 and EU FP7 HiLumi LHC - Grant Agreement 284404"
The LHC High Lu­mi­nos­ity up­grade pro­gram con­sid­ers an op­tion of using ad­di­tional cav­i­ties, op­er­at­ing at mul­ti­plies of the main RF sys­tem fre­quency of 400 MHz. Such har­monic cav­i­ties should pro­vide a pos­si­bil­ity to vary the length of col­lid­ing bunches. In order to sup­ply the re­quired har­monic volt­age sev­eral sin­gle cell su­per­con­duct­ing cav­i­ties are to be used. It is de­sir­able to house more cav­i­ties in a sin­gle cryo­stat to re­duce the num­ber of tran­si­tions be­tween "warm" and "cold" parts of the cryo­genic sys­tem. In this paper we study elec­tro­mag­netic char­ac­ter­is­tics of a chain of the sin­gle cell su­per­con­duct­ing cav­i­ties cou­pled by drifts tubes. In order to re­duce the in­flu­ence of Higher order modes (HOM) ex­cited in the struc­ture on the beam sta­bil­ity and to min­i­mize even­tual power losses we an­a­lyze the HOM pa­ra­me­ters and cal­cu­late the wake po­ten­tial decay rates due to ap­pli­ca­tion of dif­fer­ent HOM damp­ing de­vices. In par­tic­u­lar, the meth­ods of HOM damp­ing with rec­tan­gu­lar wave­guides con­nected to the drift tubes, the loads placed in the fluted and ridged drift tubes, as well as com­bi­na­tions of these meth­ods are com­pared.
Higher order modes, superconductivity, harmonic cavities 		 
 
THX02 Experience in Research, Development, Construction and Commissioning of Normally Conducting Accelerating Structures linac, coupling, simulation, cavity 278
 
  • V.V. Paramonov, L.V. Kravchuk
    RAS/INR, Moscow, Russia
  
  The ex­pe­ri­ence and re­sults of re­search, de­vel­op­ment, con­struc­tion and start of nor­mally con­duct­ing ac­cel­er­at­ing struc­tures for high in­ten­sity hadron lin­ear ac­cel­er­a­tors at medium and high en­ergii is sum­ma­rized Cre­ated meth­ods and ob­tained re­sults pro­vided con­struc­tion and start of op­er­a­tion of ac­cel­er­at­ing sys­tem in INR H− linac with de­signed en­ergy 600 MeV. The re­search re­sults allow gen­er­al­ize the prop­er­ties of high en­ergy struc­tures and de­velop meth­ods and cri­te­ria for im­prove­ments, with were re­al­ized in the de­vel­op­ment and com­mis­sion­ing of ac­cel­er­at­ing struc­tures in an­other for­eign lab­o­ra­to­ries. Bas­ing on re­search re­sults, the high en­ergy ac­cel­er­at­ing struc­ture, which sur­passes ana­logues in the total list of pa­ra­me­ters, is pro­posed and ap­proved.  
slides icon Slides THX02 [1.259 MB]  
 
THPSC16 Analysis of High Order Modes Damping Techniques for 800 MHz Single Cell Superconducting Cavities cavity, damping, dipole, luminosity 353
 
  • Ya.V. Shashkov, N.P. Sobenin
    MEPhI, Moscow, Russia
  • M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  
  Funding: Research supported by RFBR grant 13-02-00562/14 and EU FP7 HiLumi LHC - Grant Agreement 284404
The High Lu­mi­nos­ity LHC up­grade pro­gram fore­sees a pos­si­bil­ity of using the sec­ond har­monic cav­i­ties work­ing at 800 MHz for the col­lider bunch length vari­a­tion. Such har­monic cav­i­ties should pro­vide an op­por­tu­nity to vary the length of col­lid­ing bunches. In order to sup­ply the re­quired har­monic volt­age sev­eral sin­gle cell su­per­con­duct­ing cav­i­ties are to be used. Dif­fer­ent cav­ity de­signs and sev­eral higher order mode (HOM) damp­ing tech­niques are being stud­ied in order to re­duce the cav­ity HOM im­pact on the beam sta­bil­ity and to min­i­mize par­a­sitic power losses. In this paper we an­a­lyze and com­pare the HOM elec­tro­mag­netic char­ac­ter­is­tics and re­spec­tive wake po­ten­tial decay rates for cav­i­ties with grooves, fluted and ridged beam pipes. The prob­lem of Lorentz force de­tun­ing is also ad­dressed. 		 
 
THPSC17 Higher Order Modes Damping for 9-cell Structure with Modified Drift Tubes cavity, damping, quadrupole, dipole 356
 
  • Ya.V. Shashkov, A.A. Mitrofanov, N.P. Sobenin
    MEPhI, Moscow, Russia
  • V. Zvyagintsev
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  
  Funding: Research supported by RFBR grant 13-02-00562/14
This paper is fo­cused on HOM damp­ing in 9-cell su­per­con­duct­ing cav­i­ties. We are con­sid­er­ing HOM prop­a­ga­tion out­side from the cav­ity ridged and fluted drift tubes. The analy­sis of the in­flu­ence of the pa­ra­me­ters of the drift tube on the HOM damp­ing was con­ducted. The con­sid­ered meth­ods were analysed and com­pared. 		 
 
THPSC20 Multipactor in Elliptical Cavities 800 MHz cavity, electron, damping, resonance 365
 
  • M. Gusarova, I.I. Petrushina
    MEPhI, Moscow, Russia
  
  The stud­ies of the mul­ti­pact­ing dis­charge pos­si­bil­ity in el­lip­tic sin­gle-cell cav­i­ties at 800 MHz with three types of hifger order modes cou­plers were done. The ranges of the field gra­di­ents where the con­di­tions for the oc­cur­rence of first order mul­ti­pact­ing dis­charge in the equa­to­r­ial re­gion, as well as the HOM field lev­els were de­ter­mined.