Author: Hayano, H.
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TUPOW006 Six-dimensional Phase-space Rotation and its Applications 1754
  • M. Kuriki, K. Negishi
    HU/AdSM, Higashi-Hiroshima, Japan
  • H. Hayano, R. Kato, K. Ohmi, M. Satoh, Y. Seimiya, J. Urakawa
    KEK, Ibaraki, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  Funding: This work is partly supported by Grant-in-Aid for Scientific Research by MEXT, Japan (KAKENHI) 25390126.
Recent progress on the accelerator science requires optimized phase space distributions of the beam for each applications. A classical approach to satisfy the requirements is minimizing the beam emittance with a bunch charge as much as possible. This classical approach is not efficient and not compatible to the beam dynamics nature. 6D phase-space rotation, e.g. z-x and x-y, gives a way to optimize the phase space distribution for various applications. In this article, we discus possible applications of the 6D phase space rotation. The x-y rotation generates the high aspect ratio beam for linear colliders directly without DR (Damping Ring). Combination of bunch clipping with a mechanical slit and x-z rotation can generate micro-bunch structure which is applicable for FEL enhancement and drive beam for dielectric acceleration. We present our theoretical and simulation study on these applications.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW006  
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TUPOY055 Study on Electro-polishing of Nb Surface by Periodic Reverse Current Method with Sodium Hydroxide Solution 2020
  • J. Taguchi, A. Namekawa
    Nomura Plating Co, Ltd., Osaka, Japan
  • H. Hayano, T. Saeki
    KEK, Ibaraki, Japan
  • C.E. Reece, H. Tian
    JLab, Newport News, Virginia, USA
  Electropolishing is one of the best methods of Nb surface finishing of the superconducting cavity to obtain high accelerating gradient. Mixed solution of hydrofluoric acid and sulfuric acid is generally used in the electropolishing of Nb. But this solution is very dangerous and because the corrosion of the metal occurs by hydrofluoric acid, all equipment must be made of high density polyethylene or fluorocarbon resin. This causes the expensive cost of electropolishing instrument. In addition, this solution produces sulfur compound on the Nb surface in the electropolishing reaction. This sulfur compound can be field emission sources on the inner surface of cavity and degrades acceleration performance. In this poster, we report noble electropolishing method using periodic reverse current and sodium hydroxide solution. The reaction produces no sulfur content and the equipment is less expensive because the instrument can be made of usual plastic material. As the result of experiments with Nb-coupon samples, we found that the surface roughness is equivalent to the conventional electropolishing method.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY055  
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WEPMB021 Construction of Measurement System for Superconducting Characteristics on Thin-film Samples at KEK 2167
  • T. Saeki, H. Hayano, T. Kubo
    KEK, Ibaraki, Japan
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Oikawa
    Utsunomiya University, Utsunomiya, Japan
  We set up a measurement system for superconducting characteristics on thin-film samples at KEK. The system includes small-sized and middle-sized cryostats, where critical temperature, critical magnetic field, Residual Resistiviy Ratio (RRR), Superconducting RF (SRF) resistivity can be measured on thin-film samples. A small-sized cryostat has a compact refrigerator to cool down samples for the measurements of critical temperature and RRR. On the other had, we can cool down various setups with a middle-sized cryostat by using liquid helium. A thin-film sample is set into a mushroom cavity and the SRF characteristics of the thin-film sample can be measured. In another setup, a sample is set with a small coil and the third harmonic measurement is done on the sample around the critical temperature. Finally, a thin-film sample is set into the bore-center of superconducting magnet and the magnetization of sample is measured with external magnetic field around the critical temperature. This article presents the details of the system and some measurements of samples by the system.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB021  
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WEPMB024 Study on Nondestructive Inspections for Super-conducting Cavity 2174
  • H. Tongu, H. Hokonohara, Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • R. Hajima, M. Sawamura
    JAEA, Ibaraki-ken, Japan
  • H. Hayano, T. Kubo, T. Saeki, Y. Yamamoto
    KEK, Ibaraki, Japan
  Funding: The work is supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have been studying nondestructive inspections for super-conducting spoke cavities. The temperature mapping (T-map) and X-ray mapping (X-map) are powerful inspection methods to locate a hot spot during the vertical RF tests. There would be a defect under the hot spot and the defect may be the cause of a quench. Our XT-map system (a combined system of T-map and X-map) has a high resolution in space. Because the huge amount of sensor signals are multiplexed at a hi-speed scanning rate in the vicinity of the sensors, the small number of signal lines makes the installation process easy and reduces the system complexity. Our XT-map got useful results on finding a defect in vertical RF tests of International Linear collider super-conducting cavity. The XT-map system is useful as low cost nondestructive inspections for superconducting spoke cavity. The study will be reported. progresses will be reported.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB024  
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WEPMR016 Vertical Electropolishing Studies at Cornell with KEK and Marui 2295
  • F. Furuta, G.M. Ge, T. Gruber, J.J. Kaufman, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • H. Hayano, S. Kato, T. Saeki
    KEK, Ibaraki, Japan
  Cornell's SRF group has developed Vertical Electro-Polishing (VEP) and applied on 1.3GHz Niobium SRF cavities as the primary surface treatment. High-Q and high voltage performances of VEP'ed SRF cavities had been successfully demonstrated at Cornell. In 2014, new VEP R&D collaboration has started between Cornell, KEK, and Marui Galvanizing Co. Ltd. (MGI). MGI and KEK has developed their original VEP cathode named 'i-cathode Ninja'® which has four retractable wing-shape parts per cell for single-/9-cell cavities. We will report the results of VEP process using 'i-cathode Ninja'® on single cell cavity at Cornell.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR016  
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