Keyword: ECR
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MOPO059 Choke-Type Resonator for a Compact Storage Ring cavity, storage-ring, higher-order-mode, ISOL 126
 
  • L. Ovchinnikova, V.I. Shvedunov
    SINP MSU, Moscow, Russia
  • L. Ovchinnikova, V.I. Shvedunov
    LEA MSU, Moscow, Russia
  • A. Ryabov
    IHEP, Moscow Region, Russia
 
  We present the results of calculations and measurements the electrodynamic characteristics of the operating and high order modes of a choke-type resonator, intended for a 35-50 MeV storage ring, which is part of the Thomson X-ray generator.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO059  
About • paper received ※ 09 September 2018      issue date ※ 18 January 2019  
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TUPO005 Initial Beam Commissioning of LEAF at IMP rfq, emittance, MMI, acceleration 332
 
  • Y. Yang, W.P. Dou, X. Fang, Y.H. Guo, H. Jia, L. Jing, X.J. Liu, L. Lu, W. Lu, W. Ma, L.T. Sun, L.P. Sun, W. Wei, H.W. Zhao, Y.H. Zhai
    IMP/CAS, Lanzhou, People’s Republic of China
 
  A Low Energy intense-highly-charged ion Accelerator Facility (LEAF), which mainly includes an ECR ion source, LEBT and an 81.25 MHz RFQ, was designed to produce and accelerate heavy ions, from helium to uranium with A/Q between 2 and 7, to the energy of 0.5 MeV/u. The typical beam intensity is designed up to 2 emA CW for the uranium beam. The facility has been successfully commissioned with He+ (A/Q=4) and N2+ (A/Q=7) beams and accelerated the beams in the CW regime to the designed energy of 0.5 MeV/u. Beam properties and transmission efficiencies were measured, indicating a good consistency with simulated data. After having briefly recalled the project scope and parameters, this paper describes the beam commissioning strategy and detailed commissioning results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO005  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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TUPO012 Compact Multipurpors Facility - BELA rfq, linac, neutron, ion-source 349
 
  • T. Kulevoy, R. Fatkullin, A.V. Kozlov, G. Kropachev, D.N. Selesnev, A.I. Semennikov, A. Sitnikov
    ITEP, Moscow, Russia
  • T. Kulevoy
    NRC, Moscow, Russia
  • T. Kulevoy
    MEPhI, Moscow, Russia
 
  In ITEP the project of multidiscipline facility Based on ECR ion source and Linear Accelerator (BELA) is started. The injector part of facility is based on combinations of ECR ion source and dc H+ and He+ source will provide the multi beams irradiation of the reactor materials for modeling experiments. The cw RFQ and following DTL will enable the set of experimental activity both for fun-damental physics and for practical applications.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO012  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO043 New Progress with HF-free Chemical Finishing for Nb SRF Cavities cavity, SRF, niobium, controls 431
 
  • H. Tian, J. Carroll, C.E. Reece, B. Straka
    JLab, Newport News, Virginia, USA
  • T.D. Hall, M.E. Inman, R. Radhakrishnan, E.J. Taylor
    Faraday Technology, Inc., Clayton, Ohio, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Jefferson Lab has implemented a bipolar pulsed electropolishing system for final chemical processing of niobium SRF cavities. This FARADAYIC bi-polar electropolishing (BPEP) has been applied to single cells, a 7-cell CEBAF C100 cavity, and to 9-cell TESLA-style cavities.* As a mechanistic characterization of the process emerges, the critical role played by the local current density during each cathodic pulse is becoming clear. This influences system and operational parameter refinement. We present current process parameters, removal characterization, and rf performance of the processed cavities. This is the fruit of collaborative work between Jefferson Lab and Faraday Technology, Inc. directed toward the routine commercialization and industrialization of niobium cavity processing. We also present supporting data from controlled-parameter coupon studies
* E.J. Taylor, et al. "Electrochemical system and method for electropolishing superconductive radio frequency cavities" U.S. Pat. No. 9,006, 147 (& international counterparts) issued April 14, 2015.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO043  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO048 Study Progress of Pulse Laser Annealing for Niobium Film on Copper laser, niobium, experiment, cavity 438
 
  • Y. Yang, B.T. Li, X.Y. Lu, W.W. Tan, L. Xiao, D. Xie, D.Y. Yang
    PKU, Beijing, People’s Republic of China
 
  Funding: Work supported by Major Research Plan of National Natural Science Foundation of China (No. 91026001).
The recent studies of laser annealing on niobium films on copper are reported. Annealing is normally used to deal with the surface, reducing defects and even chang-ing the microstructure of the coating film. Short pulse laser can produce a sharp step temperature field on the film thickness scale (μm), which anneals the surface without substrate heated. The laser annealing experi-ments of niobium thin film sample have been carried out, and according to SEM and FIB results, Nb films melted and recrystallization occurred. Grains growing up can be observed while the power density of laser pulse in-creased.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO048  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO065 Improvement of Cavity Performance by Nitrogen Doping at KEK cavity, SRF, solenoid, accelerating-gradient 480
 
  • T. Okada, Y. Hori, E. Kako, T. Konomi, H. Sakai, K. Umemori, Y. Yamamoto
    Sokendai, Ibaraki, Japan
  • T. Dohmae, Y. Hori, E. Kako, T. Konomi, T. Saeki, T. Saeki, H. Sakai, K. Umemori, Y. Yamamoto
    KEK, Ibaraki, Japan
  • J. Kamiya
    JAEA/J-PARC, Tokai-mura, Japan
  • S. Kurosawa, K. Takeishi
    JAEA, Ibaraki-ken, Japan
 
  Nitrogen doping experiments in single-cell and 3-cell niobium cavities were carried out at KEK. After annealing at 800 deg C for 3 hours, pure nitrogen gas with a pressure of 3 Pa for 20 minutes and 3 minutes were introduced for doping in a furnace in J-PARC, respectively. Removing surface in 5 um and 20 um by electropolishing were performed prior to the vertical tests, respectively. Increases of a quality factor at 2K and reduction of the BCS resistance with respect to an accelerating gradient were observed in both cavities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO065  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO073 Niobium Sample Analysis for Nitrogen Infusion and Doping cavity, niobium, vacuum, injection 506
 
  • T. Konomi, E. Kako, S. Michizono, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
  • T. Nagata
    ULVAC, Inc., Tsukuba, Japan
  • T. Nojima
    Tohoku University, Sendai, Japan
 
  KEK has been investigating the better conditions of the heat treatment in nitrogen, which are called as nitrogen doping and nitrogen infusion. We have tried to understand the high gradient performance of the cavity from the analyses of samples which were prepared in the same conditions for the cavity. The main tools are D-SIMS for the depth profile of the elemental concentration, XPS for composition analysis and SQUID magnetometry for the critical DC magnetic field measurement. The difference in the depth profiles of the nitrogen, carbon and oxygen between the heat treatment conditions was observed in vacuum and furnace temperature of nitrogen infusion by D-SIMS and XPS. Such a difference correlates with the vortex penetration field measured by SQUID. In particular, that of nitrogen doping sample was greatly degraded, while that of nitrogen infusion sample was slightly improved. The tendency is similar to the RF high gradient test results. Details of the sample analysis are shown in this presentation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO073  
About • paper received ※ 18 September 2018      issue date ※ 18 January 2019  
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THPO050 Research on the New Cavity Structure of RFQ Accelerator With Bent Vanes at IMP rfq, cavity, simulation, impedance 802
 
  • L. Yang, T. He, Y. He, C.X. Li, L. Lu, L.P. Sun, C.C. Xing
    IMP/CAS, Lanzhou, People’s Republic of China
  • L. Yang
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
 
  A new cavity structure of RFQ accelerator with bent vanes is proposed to meet the miniaturization requirement of low frequency heavy ion accelerators at Institute of Modern Physics (IMP), Chinese Academy of Sciences. The new structure has a downsized cross section by bending vanes while keeping a certain vane lengths. It also possesses the advantages of simple cooling structure and high power efficient when used in low frequency. The new structure has obvious advantages in reducing manufacturing difficulty of cavity, cutting down project cost, enhancing facility reliability and stability.  
slides icon Slides THPO050 [1.407 MB]  
poster icon Poster THPO050 [0.398 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO050  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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THPO126 Compact H+ ECR Ion Source with Pulse Gas Valve ion-source, plasma, extraction, GUI 955
 
  • Y. Takeuchi, Y. Iwashita, H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
 
  We are developing a compact ECR H+ ion source with pulse gas valve. In the case of high current ion linac, the distance between the ion source and the first accelerating tube such as RFQ must be as short as possible to reduce the space charge effect, while operating in a high electric field a good vacuum condition is desirable. Since hydrogen gas always flows out from ion sources if the plasma chamber is filled with the gas, vacuum pumping systems have to evacuate the gas enough before the first accelerating tube. The pulse gas injection system achieved by a fast piezo gas valve can reduce the gas load on the vacuum evacuation system and is suitable for installing the ion source close to the RFQ.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO126  
About • paper received ※ 19 September 2018      issue date ※ 18 January 2019  
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