Cavities - Design
deflecting and crab cavities
Paper Title Page
THP035 Design of LHC Crab Cavities Based on DQW Cryomodule Test Experience 925
 
  • S. Verdú-Andrés
    BNL, Upton, New York, USA
  • R. Calaga, E. Cano-Pleite, R. Leuxe
    CERN, Geneva, Switzerland
  • J.A. Mitchell
    Lancaster University, Lancaster, United Kingdom
 
  Funding: Work supported by US DOE through Brookhaven Science Associates LLC under contract No. DE-SC0012704, contract No. DE-FOA-0001848 and by the European Union HL-LHC Project.
A cryomodule with two Double-Quarter Wave (DQW) cavities was designed, built and tested with the SPS beam in 2018. Each cavity was equipped with an rf pickup antenna to monitor field amplitude and phase. The pickup antenna also included a section expressly designed to couple and extract one of the Higher-Order Modes (HOM) at 1.754 GHz. The SPS beam tests evidenced direct coupling of the beam to this pickup antenna, in a similar way that a beam position monitor pickup couples to the passing beam. This undesired coupling had an impact on the RF feedback system responsible to regulate the cavity field and frequency. The present paper proposes a new DQW cavity design with improved antennae which provides adequate fundamental mode extraction while providing a reduction of both direct coupling to the beam and heat dissipation.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP035  
About • paper received ※ 23 June 2019       paper accepted ※ 02 July 2019       issue date ※ 14 August 2019  
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THP036 An Insight on the Thermal and Mechanical Numerical Evaluations for the High-Luminosity LHC Crab Cavities 929
 
  • E. Cano-Pleite, A. Amorim Carvalho, K. Artoos, R. Calaga, O. Capatina, T. Capelli, F. Carra, L. Dassa, M. Garlasché, R. Leuxe, E. Montesinos
    CERN, Geneva, Switzerland
  • J.A. Mitchell
    Lancaster University, Lancaster, United Kingdom
  • S. Verdú-Andrés
    BNL, Upton, New York, USA
 
  Funding: Research supported by the HL-LHC project
One of the key devices of the HL-LHC project are SRF crab cavities. A cryomodule with two Double Quarter Wave (DQW) crab cavities has been successfully fabricat-ed and tested with beam at CERN whereas the Radio Frequency Dipole (RFD) crab cavities are currently on its fabrication process. The paper provides an insight on the multiple calculations carried out to evaluate the thermal and mechanical performance of the DQW and RFD cavi-ties and its components. In some cases, the presence of RF fields inside the cavity volume requires the use of mul-tiphysics numerical models capable of coupling these fields with the thermal and mechanical domains. In fact, the RF field presents a strong dependency on the cavity shape, whereas the mechanical, thermal and electrical properties of the materials may substantially vary as a function of temperature, which in turn depends on the RF field. The results presented in this paper, using both cou-pled and uncoupled models, allowed elucidating the importance of physics coupling on the numerical evalua-tion of RF cavities and its components. Analyses were also of great support for the design evaluation and im-provement of future prototypes.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP036  
About • paper received ※ 21 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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FRCAA1 Overview of SRF Deflecting and Crabbing Cavities 1192
 
  • S.U. De Silva
    ODU, Norfolk, Virginia, USA
 
  Developments over the past few years on novel superconducting deflecting and crabbing cavities have introduced advanced rf geometries with improved performance, in comparison to the typical squashed elliptical cavities operating in TM110 type mode. These new structures are compact geometries operating in either TEM type or TE11-like mode. One of the key applications of such cavities is the use of crabbing systems for circular colliders in increasing the luminosity. Crabbing systems are an essential component in future colliders with intense beams and proposed electron-ion colliders. High luminosity upgrade of LHC is planned to implement crabbing systems at two interaction points. Recently, a two-cavity cryomodule with double quarter wave crabbing cavity was installed in SPS at CERN and successfully tested with the proton beam. We present the details of different superconducting deflecting and crabbing cavities and their applications, as well as the recent results of the crabbing systems test at SPS.  
slides icon Slides FRCAA1 [14.149 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAA1  
About • paper received ※ 04 July 2019       paper accepted ※ 14 August 2019       issue date ※ 14 August 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)