Author: Higashi, Y.
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THPOR042 New Quantity Describing the Pulse Shape Dependence of the High Gradient Limit in Single Cell Standing-Wave Accelerating Structures 3878
  • J. Shi, H.B. Chen, X.W. Wu
    TUB, Beijing, People's Republic of China
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • A. Grudiev, W. Wuensch
    CERN, Geneva, Switzerland
  • Y. Higashi
    KEK, Ibaraki, Japan
  • B. Spataro
    INFN/LNF, Frascati (Roma), Italy
  A new quantity has been developed to study the relationship among the breakdown rate, the pulse width and the gradient. Difference pulse shapes can be treated by introducing a Green's function. This paper describes the quantity and the results while it is applied to the data of many high-power test runs of different single-cell standing wave accelerating structures. A remarkably similar relationship between the new quantity and breakdown rate is observed from all of the test results.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR042  
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MOPMW038 Measurements of Copper RF Surface Resistance at Cryogenic Temperatures for Applications to X-Band and S-Band Accelerators 487
  • A.D. Cahill, A. Fukasawa, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • G.B. Bowden, V.A. Dolgashev, M.A. Franzi, S.G. Tantawi, P.B. Welander, C. Yoneda
    SLAC, Menlo Park, California, USA
  • J. Guo
    JLab, Newport News, Virginia, USA
  • Y. Higashi
    OIST, Onna-son, Okinawa, Japan
  Funding: Funding from DOE SCGSR and DOE/SU Contract DE-AC02-76-SF00515
Recent SLAC experiments with cryogenically cooled X-Band standing wave copper accelerating cavities have shown that these structures can operate with accelerating gradients of ~250 MV/m and low breakdown rates. These results prompted us to perform systematic studies of copper rf properties at cryogenic temperatures and low rf power. We placed copper cavities into a cryostat cooled by a pulse tube cryocooler, so cavities could be cooled to 4K. We used different shapes of cavities for the X-Band and S-Band measurements. Properties of the cavities were measured using a network analyzer. We calculated rf surface resistance from measured Q0 and Q external of the cavity at temperatures from 4 K to room temperature. The results were then compared to the theory proposed by Reuter and Sondheimer. These measurements are a part of studies with the goal of reaching very high operational accelerating gradients in normal conducting rf structures.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW038  
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MOPOY026 Baseline Design of a Proton Linac for BNCT at OIST 906
  • Y. Kondo, K. Hasegawa
    JAEA/J-PARC, Tokai-mura, Japan
  • Y. Higashi, H. Sugawara, M. Yoshioka
    OIST, Onna-son, Okinawa, Japan
  • H. Kumada
    Tsukuba University, Graduate School of Comprehensive Human Sciences, Ibaraki, Japan
  • S.-I. Kurokawa
    Cosylab, Tsukuba, Japan
  • H. Matsumoto, F. Naito
    KEK, Ibaraki, Japan
  A new facility to develop a proton linac based neutron source for boron neutron capture therapy (BNCT) and various neutron science is planned at Okinawa institute of science and technology (OIST). This facility aims to develop a prototype system of the mass production model of BNCT systems as medical apparatus. The beam power and the beam energy at the neutron production target are assumed to about 60 kW and 10 MeV, respectively. The energy will be finally decided to optimize the ratio of necessary epi-thermal and other energy of neutron. If the energy is 10 MeV, 60 kW beam power can be achieved with a beam current of 30 mA and a duty factor of 20%. The linac consists of an ECR ion source, a two-solenoid-magnet LEBT, a four-vane RFQ, and an Alvarez DTL, which are very conventional as components of proton linac. To make the accelerator compact, we are considering to use a 400-MHz band resonant frequency. As a medical apparatus, it is required that the linac system is stable and operated easily without experts of accelerator. The design of proton linac is one of the most important issues in our development. In this paper, the baseline design of this OIST BNCT linac is described.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY026  
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