Author: Sears, J.
Paper Title Page
MOPLR037 Study of the Surface and Performance of Single-Cell Nb Cavities After Vertical EP Using Ninja Cathodes 217
 
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • P. Carbonnier, F. Éozénou, Y. Gasser, L. Maurice, C. Servouin
    CEA/DSM/IRFU, France
  • F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
    KEK, Ibaraki, Japan
  • K. Ishimi
    MGI, Chiba, Japan
 
  A 1.3 GHz single-cell niobium (Nb) coupon cavity was vertically electropolished (VEPed) with three different Ninja cathodes which were specially designed for VEP of 1.3 GHz superconducting RF elliptical (ILC/Tesla type) cavities. The cathodes were fabricated to have different surface areas and different distances between cathode surface and the equator. The Ninja cathode prepared with an enhanced cathode surface area was covered with a meshed shield to avoid bubble attack on the surface of the cavity cell. It has been turned out that the anode-cathode distance and the cathode area affect surface morphology of the equator. A smooth equator surface was obtained in the cases in which the cathode surface was geometrically close to the equator or instead the cathode surface area was sufficiently larger. Two 1.3 GHz ILC/Tesla type single-cell cavities VEPed with the Ninja cathodes and using optimized conditions showed good performance in vertical tests.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR037  
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MOPLR047 Advanced Vertical Electro-Polishing studies at Cornell with Faraday 233
 
  • F. Furuta, M. Ge, T. Gruber, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T.D. Hall, M.E. Inman, S.T. Snyder, E.J. Taylor
    Faraday Technology, Inc., Clayton, Ohio, USA
 
  Cornell's SRF group and Faraday Technology Inc. have started collaborations on two phase-II SBIR projects. Both projects are aiming for the development of advanced Vertical Electro-Polishing (VEP) for Nb SRF cavities, such as HF free or acid free VEP protocols. These could be eco-friendlier alternatives for the standard, HF-based EP electrolyte used, and could bring new breakthrough performance for Nb SRF cavities. Here we give a status update and report first results from these two projects.  
poster icon Poster MOPLR047 [2.852 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR047  
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TUPLR010 Measurements and Analysis of Cavity Microphonics and Frequency Control in the Cornell ERL Main Linac Prototype Cryomodule 488
 
  • M. Ge, N. Banerjee, J. Dobbins, R.G. Eichhorn, F. Furuta, G.H. Hoffstaetter, M. Liepe, P. Quigley, J. Sears, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  The Cornell Main Linac cryomodule (MLC) is a key component in the CBETA project. The SRF cavities with high loaded-Q in the MLC are very sensitive to microphonics from mechanical vibrations. Poor frequency stability of the cavities would dramatically increase the input RF power required to maintain stable accelerating fields in the SRF cavities. In this paper, we present detailed results from microphonics measurement for the cavities in the MLC, discuss dominant vibration sources, and show vibration damping results. The current microphonics level meets the CBETA requirement of a 36MeV energy gain without applying fast tuner compensation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR010  
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TUPLR011 Performance of the Novel Cornell ERL Main Linac Prototype Cryomodule 492
 
  • F. Furuta, J. Dobbins, R.G. Eichhorn, M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  The main linac cryomodule (MLC) for the future energy-recovery linac (ERL) based X-ray light source at Cornell has been designed, fabricated, and tested. It houses six 7-cell SRF cavities with individual higher order-modes (HOMs) absorbers, cavity frequency tuners, and one magnet/BPM section. Cavities have achieved the specification values of 16.2MV/m with high-Q of 2.0·1010 in 1.8K in continuous wave (CW) mode. During initial MLC cavity testing, we encountered some field emission, reducing Q and lowering quench field. To overcome field emission and find optimal cool-down parameters, RF processing and thermal cycles with different cool-down conditions has been done. Here we report on these studies and present final results from the MLC cavity performance.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR011  
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THPRC015 Cool-Down Performance of the Cornell ERL Cryomodules 802
 
  • R.G. Eichhorn, F. Furuta, M. Ge, G.H. Hoffstaetter, M. Liepe, S.R. Markham, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich, D. Widger
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  In the framework of the ERL prototyping, Cornell University has built two cryomodules, one injector module and one prototype Main Linac Cryomodule (MLC). In 2015, the MLC was successfully cooled down for the first time. We will report details on the cool-down as well as cycle tests we did in order to achieve slow and fast cool-down of the cavities. We will also report on the improvement we made on the injector cryomodule which also included a modification of the heat exchanger can that allows now a more controlled cool-down, too.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC015  
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