Keyword: accelerating-gradient
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MOPOST017 Design and Beam Dynamics Study of Disk-Loaded Structure for Muon Linac acceleration, emittance, linac, lattice 94
 
  • K. Sumi, T. Iijima, K. Inami, Y. Sue, M. Yotsuzuka
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
  • H. Ego, T. Mibe, N. Saito, M. Yoshida
    KEK, Ibaraki, Japan
  • T. Iijima
    KMI, Nagoya, AIchi Prefecture, Japan
  • Y. Kondo, K. Moriya
    JAEA/J-PARC, Tokai-mura, Japan
  • Y. Nakazawa
    Ibaraki University, Hitachi, Ibaraki, Japan
  • M. Otani
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Takeuchi
    Kyushu University, Fukuoka, Japan
  • H.Y. Yasuda
    University of Tokyo, Tokyo, Japan
 
  The disk-loaded structures (DLS) in the muon LINAC are under development for the J-PARC muon g-2/EDM experiment. Four DLSs with an accelerating gradient of 20 MV/m take charge of muon acceleration from 40 MeV to 212 MeV, which corresponds to 70% to 94% of the speed of light. The quasi-constant gradient type TM01-2pi/3 mode DLSs with gradually varying disk spacing was designed and confirmed that the cumulative phase slip due to the mismatch between muon and phase velocity can be suppressed to less than 2 degrees at the frequency of 2592 MHz. In addition, the optimum synchronous phase and the lattice were investigated to satisfy the requirements of the total emittance less than 1.5 pi mm mrad and the momentum spread less than 0.1% in RMS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST017  
About • Received ※ 19 May 2022 — Revised ※ 09 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 20 June 2022
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TUOXSP2 Analysis of Low RRR SRF Cavities cavity, SRF, niobium, radio-frequency 783
 
  • K. Howard, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • D. Bafia, A. Grassellino
    Fermilab, Batavia, Illinois, USA
 
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. This work was supported by the University of Chicago.
Recent findings in the superconducting radio-frequency (SRF) community have shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. Success has been found in nitrogen-doping, diffusion of the native oxide into the niobium surface, and thin films of alternate superconductors atop a niobium bulk cavity. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurity profile of niobium with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of recent impurity-based improvements can be better understood and improved upon. Additionally, we perform a low temperature bake on the low RRR cavity to evaluate how the intentional addition of oxygen to the RF layer affects performance. We have found that low RRR cavities experience low temperature-dependent BCS resistance behavior more prominently than their high RRR counterparts. The results of this study have the potential to unlock a new understanding on SRF materials.
 
slides icon Slides TUOXSP2 [1.495 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOXSP2  
About • Received ※ 08 June 2022 — Accepted ※ 11 June 2022 — Issue date ※ 25 June 2022  
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TUPOTK012 Nitrogen Infusion Sample R&D at DESY cavity, niobium, vacuum, ECR 1219
 
  • C. Bate
    University of Hamburg, Hamburg, Germany
  • A. Ermakov, D. Reschke, J. Schaffran
    DESY, Hamburg, Germany
  • W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program.
Many accelerator projects such as the ILC would benefit from cavities with reduced surface resistance (high Q-values) while maintaining a high accelerating gradient. A possible way to meet the requirements is the so-called nitrogen-infusion procedure on Niobium cavities. However, a fundamental understanding and a theoretical model of this method are still missing. One important parameter is the residual resistance ratio (RRR) which is related to the impurity content of the material. We report the investigated RRR on samples in a wide temperature range in a vacuum and under a nitrogen atmosphere. This comparison made it possible to make statements about the differences in the concentration of nitrogen by varying the temperature. The samples are pure cavity-grade niobium and treated in the same manner as cavities. For this purpose, a small furnace dedicated to sample treatment was set up to change and explore the parameter space of the infusion recipe. Care was taken to achieve the highest level of purity possible in the furnace and in a pressure range of 1.0·10-8 mbar in order to meet the high requirements of nitrogen infusion.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK012  
About • Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 01 July 2022
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TUPOTK038 Next Generation SRF Cavities at Cornell University cavity, SRF, simulation, radio-frequency 1303
 
  • N.M. Verboncoeur, M. Liepe, R.D. Porter, L. Shpani
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Our goal is to develop new materials and protocols for the growth and preparation of thin-film and layered superconductors for next generation SRF cavities with higher performance for future accelerators. We are working primarily with Nb3Sn to achieve this goal, as well as other materials which aim to optimize the RF field penetration layer of the cavity. This contribution gives a general update on our most recent cavity test results. A deeper insight into RF loss distribution and dynamics during cavity testing is gained using a new global high-speed temperature mapping system (T-Map).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK038  
About • Received ※ 11 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 22 June 2022
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THPOTK042 Non-Linear Phenomena Studies in High-Gradient RF Technology for Hadrontherapy at IFIC cavity, radiation, electron, hadrontherapy 2865
 
  • P.M.R. Martinez-Reviriego, C. Blanch Gutiérrez, D. Esperante Pereira, J. Fuster, N. Fuster-Martínez, B. Gimeno, D. Gonzalez-Iglesias, P. Martín-Luna
    IFIC, Valencia, Spain
 
  High-Gradient accelerating cavities are one of the main research lines in the development of compact linear colliders. However, the operation of such cavities is currently limited by non-linear effects that are intensified at high electric fields, such as dark currents and radiation emission or RF breakdowns. A new normal-conducting High Gradient S-band Backward Travelling Wave accelerating cavity for medical application (v=0.38c) designed and constructed at CERN is being tested at IFIC. In this paper, we present experimental measurements and simulation of such non-linear effects. The main goal of these studies is to establish the viability of using these techniques in linear accelerators, in order to improve our understanding in such effects. The main goal of these studies is to determine the viability of using this techniques in linear accelerators for hadrontherapy treatments in hospitals.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK042  
About • Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 20 June 2022
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FROXSP2 Demonstration of Gradient Above 300 MV/m in Short Pulse Regime Using an X-Band Single-Cell Structure acceleration, experiment, wakefield, electron 3134
 
  • J.H. Shao, D.S. Doran, G. Ha, C.-J. Jing, W. Liu, J.G. Power, C. Whiteford, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  • H.B. Chen, X. Lin, M.M. Peng, J. Shi, H. Zha
    TUB, Beijing, People’s Republic of China
  • C. Jing
    Euclid Beamlabs, Bolingbrook, USA
 
  High gradient acceleration is one of the critical technologies required by future linear colliders, free-electron lasers, and compact linac-based applications. Among decade long effort to break state-of-the-art gradient limitation of ~100 MV/m in normal conducting structures, using RF pulses shorter than 20 ns is a promising approach based on theoretic analysis and experimental observation. In this study, we demonstrated high gradient above 300 MV/m using an X-band 11.7 GHz single-cell travelling-wave structure with 6 ns FWHM RF pulses generated by a power extractor. In comparison, a scaled 11.424 GHz structure only reached below 150 MV/m driven by 30-100 ns RF pulses from a klystron with pulse compression. The experimental results and the suggested new mechanism of beam acceleration in the Breakdown Insensitive Acceleration Regime (BIAR) are presented in this manuscript.  
slides icon Slides FROXSP2 [8.998 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-FROXSP2  
About • Received ※ 11 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 20 June 2022
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