Keyword: quadrupole
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TUP066 New Design of SSR2 Spoke Cavity for PIP II SRF Linac cavity, multipactoring, linac, HOM 600
 
  • P. Berrutti, I.V. Gonin, T.N. Khabiboulline, M. Parise, D. Passarelli, G.V. Romanov, F. Ruiu, A.I. Sukhanov, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
 
  Funding: US Department of Energy
Superconducting SSR2 spoke cavities provide acceleration of the H in PIP II SRF linac from 35 to 185 MeV. The RF and mechanical design of the SSR2 cavities has been completed and satisfies the technical requirements. However, our resent results of the high RF power tests of fully dressed SSR1 cavities show considerably strong multipacting (MP), which took significant time to process. On the other hand, the new results of the tests of balloon cavity showed significant mitigation of MP. In this paper we present the results of the improved design of the SSR2 cavity, based on the balloon cavity concept. The electromagnetic design is presented, including RF parameter optimization, MP simulations, field asymmetry analysis, High Order Mode (HOM) calculations. Mechanical analysis of the dressed cavity is presented also, which includes Lorentz Force Detuning optimization, and reduction of the cavity resonance frequency sensitivity versus He pressure fluctuations. The design completely satisfies the PIP II technical requirements.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP066  
About • paper received ※ 21 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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TUP073 Superconducting Thin Films Characterization at HZB with the Quadrupole Resonator cavity, SRF, niobium, FEL 616
 
  • D.B. Tikhonov, S. Keckert, J. Knobloch, O. Kugeler, Y. Tamashevich
    HZB, Berlin, Germany
  • A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
 
  Funding: EASITrain - European Advanced Superconductivity Innovation and Training. This Marie Sklodowska-Curie Action Innovative Training Networks founded by H2020 under Grant Agreement no. 764879
Superconducting thin films have great potential as post-Nb material for use in SRF applications in future accelerators and industry. To test the RF-performance of such films in practice, would require the building and coating of a full RF cavity. Deposition of thin films on such scales in test facilities are challenging, in particular when curved surfaces have to be coated. This greatly complicates their systematic research. In this contribution we report on the method we use to characterize small and flat thin film samples (Deposited onto both Nb and Cu substrates) in an actual cavity named the Quadrupole Resonator (QPR). We also summarize the latest measurement results of NbTiN thin films. The Quadrupole Resonator at HZB is a tool that is able to perform SRF characterizations at frequencies ~415, 847, 1300 MHz with RF fields using an RF-DC power compensation technique.
 
poster icon Poster TUP073 [2.318 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP073  
About • paper received ※ 23 June 2019       paper accepted ※ 02 July 2019       issue date ※ 14 August 2019  
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THFUA1 RF Characterization of an S-I-S’ Multilayer Sample niobium, ECR, SRF, cavity 800
 
  • S. Keckert, J. Knobloch, O. Kugeler, D.B. Tikhonov
    HZB, Berlin, Germany
  • A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
 
  S-I-S’ multilayers promise to boost the performance of bulk superconductors in terms of maximum field and surface resistance. At HZB, RF-surface resistance measurements were performed with a Quadrupole Resonator (QPR) and an S-I-S’ sample (75 nm NbTiN on 15 nm AlN insulator on bulk Nb) prepared at JLab. Measurements were performed at 414, 845, and 1286 MHz at sample temperatures from 2 K up to well above the transition temperature of NbTiN of ~17.3 K. The Rs exhibits an unexpected temperature dependence: Rather than rising monotonically, as expected from BCS theory, a local maximum is observed. There is a temperature range where Rs decreases with increasing temperature. Such behavior indicates that an additional interaction between the superconducting layers may have to be included in the surface resistance model. Measurements of the baseline Nb sample prior to coating exhibited no such behavior; hence systematic measurement errors can be excluded as the explanation. The maximum field was limited by a hard magnetic quench near 20 mT, close to Hc1 of NbTiN, suggesting that the sample is limited by early flux penetration.  
slides icon Slides THFUA1 [1.004 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THFUA1  
About • paper received ※ 22 June 2019       paper accepted ※ 03 July 2019       issue date ※ 14 August 2019  
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THP004 Design and Fabrication of a Quadrupole-Resonator for Sample R&D cavity, SRF, simulation, niobium 838
 
  • R. Monroy-Villa, D. Reschke, M. Wenskat
    DESY, Hamburg, Germany
  • W. Hillert, R. Monroy-Villa, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Keckert, O. Kugeler, D.B. Tikhonov
    HZB, Berlin, Germany
  • P. Putek, S.G. Zadeh, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • U. van Rienen
    University of Rostock, Rostock, Germany
 
  Being able to obtain BCS and material properties from the same surface is necessary to gain a fundamental understanding of the evolution of SRF surfaces. A test resonator which will allow to obtain BCS properties from samples is currently under development at the University of Hamburg and DESY and is based on the Quadrupole Resonators developed and operated at CERN and HZB. The current status of the necessary infrastructure, the procurement process and design considerations are shown. In addition, an outline of the planed R&D project with the Quadrupole Resonator will be presented and first RF measurements and surface analysis results of samples will be shown  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP004  
About • paper received ※ 23 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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THP045 Improvements to the Cornell Sample Host System cavity, niobium, SRF, coupling 956
 
  • T.E. Oseroff, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  RF characterization of arbitrary superconducting samples has been of interest for many years but, due to the experimental complexities, has never been achieved to its full potential. A TE mode niobium sample host cavity has been used at Cornell to characterize the RF performance of 5" (12.7 cm) diameter sample plates. It was designed and built in 2012 – 2013 and since then has encountered a range of problems. The focus of this work is to highlight these and to present solutions to assist future researchers hoping to design novel RF characterization instruments. Topics covered include coupler design, cryostat support structure, sample preparation, and a discussion of potential systematic errors introduced by the data extraction and calibration methods applied to this device.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP045  
About • paper received ※ 01 July 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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THP083 Quadrupole Scan Transverse Emittance Measurements at HZDR ELBE emittance, focusing, experiment, electron 1100
 
  • S. Ma, A. Arnold, A.A. Ryzhov, J. Schaber, J. Teichert, R. Xiang, K. Zhou
    HZDR, Dresden, Germany
 
  Two quadrupoles and one screen are used for beam transverse emittance measurements at HZDR ELBE. In this paper, the emittance calculated with two different methods, one with thin-lens approximation and the other one without this approximation, are compared and analized. To analyze the measurement error, quadrupole calibration is need. Two aspects about quadrupole analysis are made. The first one is quadrupole’s effective length and strength and the second one is quadrupole’s converged or diverged ability in reality.  
poster icon Poster THP083 [1.726 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP083  
About • paper received ※ 25 June 2019       paper accepted ※ 03 July 2019       issue date ※ 14 August 2019  
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THP102 Uncertainty Quantification of a Quadrupole-Resonator for Radio Frequency Characterization of Superconductors cavity, HOM, SRF, radio-frequency 1168
 
  • P. Putek, S. Gorgi Zadeh, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • W. Hillert
    ELSA, Bonn, Germany
  • W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • M. Wenskat
    DESY, Hamburg, Germany
  • U. van Rienen
    University of Rostock, Rostock, Germany
 
  Funding: This work has been supported by the German Federal Ministry for Research and Education BMBF under contract 05H18HRRB1.
To explore the fundamental properties of superconducting materials used in modern particle accelerators, high precision surface resistance measurements in a dedicated testing equipment is of key importance. The quadrupole resonator, originally developed at CERN, and then successfully modified at the Helmholtz-Zentrum Berlin, is ideally suited for characterization of samples at temperatures of 1.8 K to > 20 K, RF fields of up to 120 mT and frequencies of 433 MHz, 866 MHz and 1.3 GHz. In the past years, this set-up has been subject of intensive research on both its capabilities and limitations. Yet, one of the main challenges is the accuracy of the surface resistance measurement, which is determined by both the uncertainty in the RF measurement and manufacturing imperfections related to the production tolerances such as quenching and chemical polishing processes, etc. In this contribution, we focus on the influence of key geometrical parameters on operating the quadrupole resonator at the third mode, since the surface resistance measurement shows some unexpected behavior for this frequency.
* Design and Fabrication of a Quadrupole-Resonator for Sample R&D by M. Wenskat, W. Hillert, et al.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP102  
About • paper received ※ 25 June 2019       paper accepted ※ 29 June 2019       issue date ※ 14 August 2019  
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