WEYGBF —  MC7 Orals   (02-May-18   11:00—12:30)
Chair: I.S. Ko, PAL, Pohang, Kyungbuk, Republic of Korea
Paper Title Page
Development and Construction of Low-Beta Superconducting Cavities for Large Accelerators  
  • P.N. Ostroumov
    FRIB, East Lansing, USA
  Placeholder for Peter Ostroumov's pop-up talk  
slides icon Slides WEYGBF1 [11.069 MB]  
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Pathway to High Gradients in Superconducting rf Cavities by Avoiding Flux Dissipation  
  • A.S. Romanenko
    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.
It is currently believed in the field of SRF that the limit of the achievable accelerating gradients is set by the DC superheating field value, which guides most of the theoretical and experimental studies in this direction. However, it was recently proposed* that another mechanism is currently enabling both the existing SRF cavities with the quench field in excess of niobium Hc1, and providing the path forward to higher gradients, namely the vortex nucleation time slower than the rf period. If true, differently from currently pursued higher DC Hsh materials (e.g. Nb3Sn, MgB2 etc) or multi-layered structures, the new proposed directions are doping of the top niobium surface with special types of inelastic electron-phonon scattering "slowing down" impurities, or coating with thin layers of LOW (and not high) Tc superconductors. Both experimental and theoretical progress at Fermilab in this new area will be presented.
*A. Romanenko, TTC Topical Workshop - RF Superconductivity: Pushing Cavity Performance Limits, Fermilab, Batavia, IL, 2017, https://indico.fnal.gov/event/15177/session/3/contribution/27
slides icon Slides WEYGBF2 [3.785 MB]  
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WEYGBF3 Nb3Sn Multicell Cavity Coating at JLab 1798
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G. Ciovati, G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  • I.P. Parajuli, MNS. Sayeed
    ODU, Norfolk, Virginia, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics.
Following encouraging results with Nb3Sn-coated R&D cavities, the existing coating system was upgraded to allow for Nb3Sn coating of CEBAF accelerator cavities. The upgrade was designed to allow Nb3Sn coating of original CEBAF 5-cell cavities with the vapor diffusion technique. Several CEBAF cavities were coated in the upgraded system to investigate vapor diffusion coatings on extended structures. Witness samples coated along with the cavities were characterized with material science techniques, while coated cavities were measured at 4 and 2 K. The progress, lessons learned, and the pathforward are discussed.
slides icon Slides WEYGBF3 [2.386 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBF3  
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WEYGBF4 Development of a Solid-State Pulse Generator Driving Kicker Magnets for a Novel Injection System of a Low Emittance Storage Ring 1804
  • T. Inagaki, H. Tanaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • H. Akikawa, K. Sato
    Nihon Koshuha Co. Ltd, Yokohama, Japan
  • K. Fukami, C. Kondo, S. Takano
    Japan Synchrotron Radiation Research Institute (JASRI), RIKEN SPring-8 Center, Hyogo, Japan
  Funding: Funded by MEXT Japan
A next generation electron storage ring represented by a diffraction-limited light source pursues an extremely low emittance leading to a small dynamic aperture and short beam lifetime. The top-up injection is hence indispensable to keep the stored beam current. The beam orbit fluctuation caused by the injection magnets should seriously obstruct utilization of an electron beam with sharp transverse profile. In order to solve these problems, a novel off-axis in-vacuum beam injection system was proposed. In the system, twin kicker magnets driven by a single solid-state pulsed power supply to launch a linear pi- bump orbit is the key to suppress the horizontal orbit fluctuation down to a level of several microns. Here, a big challenge is to achieve the magnetic field identity of the two kickers within an accuracy of 0.1%. This presentation overviews the proposed injection system and reports the development status focusing on the solid-state pulse generator.
slides icon Slides WEYGBF4 [3.067 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBF4  
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