Author: Liepe, M.
Paper Title Page
TUPO054 Fundamental Studies of Impurity Doping in 1.3 GHz and Higher Frequency SRF Cavities 458
SPWR018   use link to see paper's listing under its alternate paper code  
TUOP01   use link to see paper's listing under its alternate paper code  
 
  • J.T. Maniscalco, P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  As the demand for more powerful, more efficient, and smaller superconducting RF accelerators continues to increase, both impurity doping and high-frequency cavities (> 1.3 GHz) have become hot topics for fundamental research because of their potential to significantly decrease surface losses and cost respectively. In this report, we present recent experimental and theoretical results on undoped and nitrogen-doped high-frequency cavities and on alternative doping agents in traditional 1.3 GHz cavities, with a focus on understanding the fundamental science of impurity doping.  
slides icon Slides TUPO054 [1.956 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO054  
About • paper received ※ 16 September 2018      issue date ※ 18 January 2019  
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TUPO055 Next Generation Nb3Sn SRF Cavities for Linear Accelerators 462
 
  • R.D. Porter, D.L. Hall, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T. Arias, P. Cueva, D.A. Muller, N. Sitaraman
    Cornell University, Ithaca, New York, USA
 
  Niobium-3 Tin (Nb3Sn) is a very promising alternative material for SRF accelerator cavities. The material can achieve higher quality factors, higher temperature operation and potentially higher accelerating gradients (~ 96 MV/m) compared to conventional niobium. This material is formed by vaporizing Sn in a high temperature vacuum furnace and letting the Sn absorb into a Nb substrate to form a 2-3 um Nb3Sn layer. Current Nb3Sn cavities produced at Cornell achieve Q ~ 1010 at 4.2 K and 17 MV/m. Here we present a summary of the current performance of Nb3Sn cavities at Cornell and recent progress in improving the accelerating gradient.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO055  
About • paper received ※ 20 September 2018      issue date ※ 18 January 2019  
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TUPO057 Low-temperature Baking and Infusion Studies for High-gradient ILC SRF Cavities 466
 
  • M. Ge, P.N. Koufalis, G. Kulina, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Low-temperature infusion has become a hot-topic in SRF researches recently. Past results show that low-temperature infusion can produce high quality factor at medium accelerating fields. Also, 75°C baking recently has been shown to improve accelerating gradients of SRF cavities. Hence these treatments are very promising for reducing cost of the ILC. In this work, we present latest results of low temperature infusion and baking, showing that these treatments can improve SRF cavities performance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO057  
About • paper received ※ 19 September 2018      issue date ※ 18 January 2019  
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TUPO058 Cool Down Studies for the LCLS-II Project 470
 
  • M. Ge, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • D. Gonnella
    SLAC, Menlo Park, California, USA
  • J. Sears
    Cornell University, Ithaca, New York, USA
 
  The quality factor of the nitrogen-doped SRF cavities for the LCLS-II project are strongly impacted by cool down speed. A sufficiently fast cool down speed can produce large thermal gradient across a cavity and sufficiently expel magnetic flux when the cavity wall passes from the normal-conducting to the superconducting state. However, instrumentation in LCLS-II production cryomodules has been kept at a minimum, and additional information during the cool down of the modules is therefore desirable. In this work, we study if and how RF data can be used during cavity cool-down to determine the transition speeds of the individual cavities in the LCLS-II linac.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO058  
About • paper received ※ 19 September 2018      issue date ※ 18 January 2019  
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TUPO059 Latest Results of Salt Based Bipolar Electro-polishing R&D at Cornell 473
 
  • M. Ge, F. Furuta, T. Gruber, J.J. Kaufman, M. Liepe, R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T.D. Hall, R. Radhakrishnan, S.T. Snyder, E.J. Taylor
    Faraday Technology, Inc., Clayton, Ohio, USA
 
  Acid free electropolishing would be safer to use and friendlier to the environment. A collaboration, sup-ported by the DOE SBIR Phase-II program, between Faraday Technology Inc. and Cornell University focused on salt-based bipolar electropolishing (BEP). In this paper, we present the latest salt-based BEP results. The superconducting performance of a single-cell 1.3GHz cavity has been carefully analyzed, showing that salt-based BEP is promising, but still has large room for improvement.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO059  
About • paper received ※ 19 September 2018      issue date ※ 18 January 2019  
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WE1A02
CBETA, a 4-turn ERL Based on SRF Linacs and Permanent Magnet Beam Transport  
 
  • G.H. Hoffstaetter, N. Banerjee, J. Barley, A.C. Bartnik, I.V. Bazarov, D.C. Burke, J.A. Crittenden, L. Cultrera, J. Dobbins, F. Furuta, R.E. Gallagher, M. Ge, C.M. Gulliford, B.K. Heltsley, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, W. Lou, J.R. Patterson, P. Quigley, D.M. Sabol, D. Sagan, J. Sears, C.H. Shore, E.N. Smith, K.W. Smolenski, V. Veshcherevich, D. Widger
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg, S.J. Brooks, C. Liu, G.J. Mahler, F. Méot, R.J. Michnoff, M.G. Minty, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, H. Witte
    BNL, Upton, Long Island, New York, USA
  • D. Jusic
    Cornell University, Ithaca, New York, USA
 
  A collaboration between Cornell University and Brookhaven National Laboratory has designed a novel accelerator and is constructing it at Cornell: CBETA, the Cornell-BNL ERL Test Accelerator. The ERL technology that has been prototyped at Cornell for many years is being used, including a DC electron source and an SRF injector Linac with world-record current and normalized brightness in a bunch train, a high-current linac cryomodule optimized for ERLs, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams. BNL has designed a multi-turn ERL and a recirculating linac for eRHIC; in both designs the beam is transported many times around the 4 km long RHIC tunnel. The number of transport lines is minimized by using two arcs with Fixed Field Alternating Gradient design. This technique will be tested in CBETA, which has a single return for the 4-beam energies with strongly-focusing permanent magnets of Halbach type. The high-brightness beam with 150 MeV and up to 40 mA will have applications for Electron Ion Colliders (EICs), e.g. for their electron cooling, and for applications in industry, in nuclear physics, and in X-ray science.  
slides icon Slides WE1A02 [6.367 MB]  
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