Author: Calaga, R.
Paper Title Page
TUPOTK015 HOM Coupler Design and Optimization for the FCC-ee W Working Point 1230
SUSPMF108   use link to see paper's listing under its alternate paper code  
 
  • S. Udongwo, S.G. Zadeh, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • R. Calaga
    CERN, Meyrin, Switzerland
 
  Funding: Funded by CERN under ADDENDUM FCC-GOV-CC-00213 (KE4978/ ATS) to FCC-GOV-CC- 0213/2431149/KE4978 VERSION 1.0.
The Future Circular electron-positron Collider (FCC-ee) is planned to operate with beam energies from 45.6 to 182.5 GeV and beam currents from 5.4 to 1390 mA. The purpose is to study the properties of the Z-, W- and Higgs boson and the top and anti-top quarks in four operation points. The beam current of 147 mA of the W working point requires particular care to string damp HOMs. This paper proposes 2-cell 400 MHz SRF cavities with improved damping as an alternative to the baseline 4-cell cavities for this working point. The resulting impedance of the HOM-damped cavity is then calculated and compared with the impedance budget.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK015  
About • Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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TUPOTK064 HL-LHC Crab Cavity HOM Couplers: Challenges and Results 1374
 
  • J.A. Mitchell, R. Calaga, E. Montesinos
    CERN, Meyrin, Switzerland
 
  To compensate for the detrimental effect of the crossing angle on luminosity production in the High Luminosity Large Hadron Collider’s (HL-LHC) interaction regions, superconducting crab cavities (vertical and horizontal) will be installed at the two interaction regions of the ATLAS and CMS experiments. Both cavity designs use multiple Higher Order Mode (HOM) couplers to reduce beam instabilities and heat loads caused by the very high proton current in the HL-LHC. The conceptual RF designs of the HOM couplers are firstly presented, evaluating HOM damping requirements, fundamental mode rejection and dynamic heat load constraints. A special focus is given to the coupler’s characteristic impedance (Z0), to improve the robustness during transport and operation. Following this, RF measurements of the HOM couplers before installation, installed on the superconducting cavities and with a circulating proton beam are detailed, analysing deviations from the simulated cases.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK064  
About • Received ※ 07 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 10 July 2022
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WEOZSP2 Suppression of Crab Cavity Noise Induced Emittance Growth by Transverse Beam Coupling Impedance 1659
SUSPMF068   use link to see paper's listing under its alternate paper code  
 
  • N. Triantafyllou, A. Wolski
    The University of Liverpool, Liverpool, United Kingdom
  • F. Antoniou, H. Bartosik, P. Baudrenghien, X. Buffat, R. Calaga, Y. Papaphilippou
    CERN, Meyrin, Switzerland
  • T. Mastoridis
    CalPoly, San Luis Obispo, California, USA
 
  Crab Cavities are a key component of the High Luminosity LHC (HL-LHC) upgrade, as they aim to minimize the luminosity reduction caused by the crossing angle. Two superconducting crab cavities were installed in the Super Proton Synchrotron (SPS) at CERN in 2018 to test their operation in a proton machine for the first time. An important point to consider is the increase in transverse emittance induced by noise in the Low-Level RF (LLRF) system. During the first experimental campaign in 2018, the measured emittance growth was found to be a factor of 4 lower than predicted by the available analytical models. In this report, the effects of transverse beam impedance in the presence of CC LLRF noise on transverse emittance growth are presented and the results of the second experimental campaign, which took place in the SPS in 2021, are discussed.  
slides icon Slides WEOZSP2 [2.694 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOZSP2  
About • Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 15 June 2022
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WEPOPT009 Operational Scenario of First High Luminosity LHC Run 1846
 
  • R. Tomás García, G. Arduini, P. Baudrenghien, R. Bruce, O.S. Brüning, X. Buffat, R. Calaga, F. Cerutti, R. De Maria, J. Dilly, I. Efthymiopoulos, M. Giovannozzi, P.D. Hermes, G. Iadarola, O.R. Jones, S. Kostoglou, E.H. Maclean, N. Mounet, E. Métral, Y. Papaphilippou, S. Redaelli, G. Sterbini, H. Timko, F.F. Van der Veken, J. Wenninger, M. Zerlauth
    CERN, Meyrin, Switzerland
 
  A new scenario for the first operational run of the HL-LHC era (Run 4) has been recently developed to accommodate a period of performance ramp-up to achieve an annual integrated luminosity close to the nominal HL-LHC design. The operational scenario in terms of beam parameters and machine settings, as well as the different phases, are described here along with the impact of potential delays on key hardware components.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT009  
About • Received ※ 19 May 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 09 July 2022
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