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.