Keyword: pick-up
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MOP036 Microphonics Suppression Study in ARIEL e-Linac Cryomodules cavity, cryomodule, GUI, linac 136
 
  • Y. Ma, K. Fong, J.J. Keir, D. Kishi, S.R. Koscielniak, D. Lang, R.E. Laxdal, S. Liu, R.S. Sekhon, X. Wang
    TRIUMF, Vancouver, Canada
 
  Now the stage of the 30 MeV portion of ARIEL (The Advanced Rare Isotope Laboratory) e-Linac (1.3 GHz, SRF) is under commissioning which includes an injector cryomodule (ICM) with a single nine-cell cavity and the 1st accelerator cryomodule (ACM1) with two cavities configuration. The two ACM1 cavities are driven by a single klystron with vector-sum control and running in CW mode. We have observed a ponderomotive instability in ACM1 driven by the Lorentz force and seeded through microphonics that impacts beam stability [1-5]. Extensive damping has been implemented during a recent shut-down. The beam test results show 20 MeV acceleration gain can be reached by ACM1. A fast piezoelectric (Pie-zo) tuner is under development to allow a fast tuning compensation for the e-Linac cavities. In this paper, the progress of the microphonics suppression of Cryomod-ules is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP036  
About • paper received ※ 24 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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MOP062 Fabrication of SRF Cavity coupling, vacuum, cavity, SRF 214
 
  • K. Kanaoka, H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa
    MHI-MS, Kobe, Japan
  • E. Kako, K. Umemori
    KEK, Ibaraki, Japan
 
  Mitsubishi Heavy Industries Machinery Systems (MHI-MS) have developed manufacturing process of superconducting cavities for a long time. In this presentation, recent progress will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP062  
About • paper received ※ 23 June 2019       paper accepted ※ 05 July 2019       issue date ※ 14 August 2019  
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MOP074 External Q Measurement for Quarter Wave Resonators in RISP cavity, cryomodule, simulation, coupling 245
 
  • S. Lee, B.H. Choi, M.O. Hyun, Y. Jung, J.W. Kim, Y. Kim, J. Lee, K.T. Seol
    IBS, Daejeon, Republic of Korea
 
  A heavy-ion accelerator facility is under construction for Rare Isotope Science Project(RISP) in Korea. The super conducting cavity, quarter wave resonator(QWR) which consists of driver and post linear accelerator system, is now in the mass production phase. In order to develop the QWR cavity and cryomodule, the RF couplers are fabriacated and tested. In this paper, the study of external Q for QWR coupler will be described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP074  
About • paper received ※ 21 June 2019       paper accepted ※ 29 June 2019       issue date ※ 14 August 2019  
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MOP086 Conditioning of the First Mass Production Power Couplers for the ESS Elliptical Cavities vacuum, electron, cavity, Windows 288
 
  • C. Arcambal, M. Baudrier, P. Bosland, G. Devanz, T. Hamelin, C. Marchand, M. Oublaid, G. Perreu, S. Regnaud, C. Servouin, C. Simon
    CEA-DRF-IRFU, France
  • G. Monnereau
    CEA-IRFU, Gif-sur-Yvette, France
 
  In the framework of the European Spallation Source (ESS), CEA Paris-Saclay is in charge of the delivery of 9 medium beta (β = 0.67) and 21 high beta (β = 0.86) cryomodules. Each cryomodule is composed of 4 cavities equipped with RF (Radio Frequency) power couplers (704.42 MHz, 1.1 MW maximum peak power, repetition rate=14 Hz, RF pulse width > 3.1 ms). Ten prototype power couplers have been manufactured to validate the design and the performance. Currently the mass production of the 120 couplers started and the six first pre-series medium beta couplers have been successfully conditioned. The achievement of this milestone allowed us to launch the production of the remaining 30 medium beta couplers. This paper presents the conditioning of the pre-series couplers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP086  
About • paper received ※ 23 June 2019       paper accepted ※ 29 June 2019       issue date ※ 14 August 2019  
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TUP064 Flashover on RF Window of HWR SRF Cavity cavity, electron, SRF, linac 597
 
  • X. Liu, Z. Gao, Y. He, G. Huang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Breakdown on the RF ceramic windows always happen in different kinds of accelerator. It is one of the main limitations in current day superconducting cavities and couplers. The PT signal trip caused by discharge on the surface of RF ceramic window lead LLRF control system trip which affect the stable operation of the superconducting linac. Simulation of field emission electron trajectory in superconducting cavity and experimental measurements of the frequency of the pickup signal trip have been performed. A lot of aged window with characteristics of flashover were studied by means of material characterization. The flashover on the surface of RF ceramic window caused by electrons and field emission provide the origin of initial electrons. A modified design of the pickup antenna have solved the PT pickup trip problem.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP064  
About • paper received ※ 23 June 2019       paper accepted ※ 04 July 2019       issue date ※ 14 August 2019  
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THP035 Design of LHC Crab Cavities Based on DQW Cryomodule Test Experience cavity, coupling, HOM, controls 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 cavity, coupling, electromagnetic-fields, experiment 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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