SRF Technology - Ancillaries
power coupler / antennas
Paper Title Page
MOP050 Modular Power Couplers for 217 MHz Superconducting CH-Cavities 168
SUSP034   use link to see paper's listing under its alternate paper code  
 
  • J. List, K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, M. Miski-Oglu
    HIM, Mainz, Germany
  • K. Aulenbacher, W.A. Barth, C. Burandt, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, A. Schnase, S. Yaramyshev
    GSI, Darmstadt, Germany
  • K. Aulenbacher, F.D. Dziuba, S. Lauber, J. List
    IKP, Mainz, Germany
  • M. Basten, M. Busch, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
 
  The HELmholtz LInear ACcelerator (HELIAC) is being developed by a collaboration of HIM, GSI and the Goethe University of Frankfurt. It is a superconducting (sc), continuous wave (cw) heavy ion linac that comprises novel Crossbar H-mode (CH) cavities. In April 2017 and November/December 2018 the first sc CH-cavity of the linac was tested with beam. The first operations of the cavity showed, that the prototype of the rf power coupler needs to be further improved. A new version of the coupler is being designed at the HIM. Further development will mainly be focused on the heat input into the cryostat caused by the coupler. Also the coupler will have a modular design. This improves the accessibility and maintenance of the coupler. Various cryogenic and rf tests are foreseen, to provide a reliable, fail-safe coupler for the HELIAC. For an enhanced coupler test stand a movable reflector has been designed and built. With its movable semi-reflective element, it allows to operate the test stand in a resonance mode. In addition, the movable reflector can vary the coupling factor. This contribution discusses the recent coupler R&D for the HELIAC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP050  
About • paper received ※ 21 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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MOP073 The Study of High Power Couplers for CIADS 241
SUSP007   use link to see paper's listing under its alternate paper code  
 
  • Z.Q. Lin, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, C.L. Li, Y.M. Li, M. Lu, F. Pan, T. Tan, R.X. Wang, Z. Xue, Z.Q. Yang, S.X. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  High power couplers with high operation reliability are needed for the superconducting cavities used in the Linac of CiADS project at IMP. This paper will report two works on high power coupler. The DC bias structure of the coupler was optimized to suppress the multipacting effect, where the series resistors were introduced to the wire of the DC bias to reduce the field propagating along the DC bias’s wire. For the purpose of significantly decreasing the power needed to condition the coupler, we designed a new RF conditioning scheme, in which the coupler served as a standing wave resonator, and the positions of the crests and troughs of the wave were tunable. The details of the design mentioned above will be depicted.  
poster icon Poster MOP073 [14.677 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP073  
About • paper received ※ 25 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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MOP074 External Q Measurement for Quarter Wave Resonators in RISP 245
 
  • S. Lee, B.H. Choi, M.O. Hyun, Y. Jung, J.W. Kim, Y. Kim, J. Lee, K.T. Seol
    IBS, Daejeon, Republic of Korea
 
  A heavy-ion accelerator facility is under construction for Rare Isotope Science Project(RISP) in Korea. The super conducting cavity, quarter wave resonator(QWR) which consists of driver and post linear accelerator system, is now in the mass production phase. In order to develop the QWR cavity and cryomodule, the RF couplers are fabriacated and tested. In this paper, the study of external Q for QWR coupler will be described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP074  
About • paper received ※ 21 June 2019       paper accepted ※ 29 June 2019       issue date ※ 14 August 2019  
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MOP075 Design of RF Power Coupler Transmitting both 162.5 MHz and 81.25 MHz Power to SRF Cavities for BISOL R&D Research 249
 
  • F. Zhu, M. Chen, A.Q. Cheng, J.K. Hao, S.W. Quan, F. Wang
    PKU, Beijing, People’s Republic of China
 
  Beijing isotope separation on line type rare ion beam facility (BISOL) is a proposed facility which has two superconducting RF linacs. One is a high intense driver linac which adopts half wave resonators (HWRs), and the other is the low current post-accelerator which includes quarter wave resonators (QWRs). For the pre-research of BISOL, a cryomodul which can do the horizontal test of both 81.25 MHz QWR for the post-accelerator and 162.5 MHz HWR for the driver accelerator with the proper external quality factor. For this purpose, Peking University are developing a coupler which can transfer 5 kW power to the 81.25 MHz QWR or cw 20 kW power to the 162.5 MHz HWR cavity. The electromagnetic optimization, Multipacting simulation, thermal analysis and detail structure of the coupler will be presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP075  
About • paper received ※ 21 June 2019       paper accepted ※ 02 July 2019       issue date ※ 14 August 2019  
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MOP076 Fundamental Power Coupler Design for a 325 MHz Balloon SSR Cavity 252
 
  • R.E. Laxdal, Y. Ma, B. Matheson, B.S. Waraich, Z.Y. Yao, V. Zvyagintsev
    TRIUMF, Vancouver, Canada
 
  TRIUMF has designed, fabricated and tested the first balloon variant of the single spoke resonator at 325 MHz and β=0.3. TRIUMF has also designed a 6 kW fundamental power coupler as part of the development. The design of the coupler will be presented.  
poster icon Poster MOP076 [1.282 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP076  
About • paper received ※ 24 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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MOP077 Ceramic Study on RF Windows for Power Coupler, Waveguide, and Klystron in Particle Accelerator 255
 
  • Y. Yamamoto, S. Michizono
    KEK, Ibaraki, Japan
 
  R&Ds on different types of ceramic used in power coupler, waveguide, and klystron for particle accelerators are under progress in Center of Innovation (COI) at KEK, and at some outside companies. There are five important parameters on the properties of ceramics; that is, relative permittivity, dielectric loss tangent, surface and volume resistivity, and secondary electron emission coefficient. For measurements of these parameters, eight kinds of ceramic samples supplied from five vendors have been measured using three different measurement systems since 2017. In this report, the recent results for these studies will be presented in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP077  
About • paper received ※ 22 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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MOP078 Adjustable Power Coupler for NICA HWR Cavities 260
 
  • S.V. Matsievskiy, M.V. Lalayan
    MEPhI, Moscow, Russia
  • D. Bychanok
    INP BSU, Minsk, Belarus
  • M. Gusarova
    JINR, Dubna, Moscow Region, Russia
 
  Current results on input power coupler development for Half-Wave superconducting accelerating cavity proposed for Nuclotron-based Ion Collider fAcility (NICA) collider injector upgrade are discussed. Two coupler designs are considered, first one is a low-power coupler for cavity tests and the second one is a high-power operational coupler. Both devices are of coaxial type with capacitive coupling; high-power coupler utilizes single ceramic vacuum window. NICA is designed to accelerate different types of ions. Due to the variable intensity of ion sources, beam current will vary in wide range. In order to ensure efficient acceleration, power coupler must be highly adjustable in terms of coupling coefficient. This introduces excessive mechanical stress in the ceramic RF window due to the bellows deformation. In order to mitigate this effect bellows were substituted with sliding contacts. This paper discusses new coupler design and its electrical, mechanical and thermal properties.  
poster icon Poster MOP078 [1.296 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP078  
About • paper received ※ 23 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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MOP080 Latest Progress in Designs and Testings of PIP-II Power Couplers 263
 
  • S. Kazakov, B.M. Hanna, O.V. Pronitchev, N. Solyak
    Fermilab, Batavia, Illinois, USA
 
  Proton Improvement Plan – II (PIP-II) project is under go in Fermi National Laboratory. Main part of the project is 800 MeV proton superconducting accelerator which includes 116 superconducting cavities of 5 different types and three 162.5, 325 and 650 MHz frequencies. Key elements of accelerator which determine a reliable operation are main couplers for superconducting cavities. This paper describes the latest progress in design and testing of main couplers for PIP-II projects.  
poster icon Poster MOP080 [0.881 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP080  
About • paper received ※ 18 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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MOP081 Considerations for Efficient RF Operation for the Advanced cw-Linac Demonstrator at GSI 267
 
  • C. Burandt, K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, S. Yaramyshev
    HIM, Mainz, Germany
  • K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, A. Schnase, S. Yaramyshev
    GSI, Darmstadt, Germany
  • K. Aulenbacher, F.D. Dziuba, S. Lauber, J. List
    IKP, Mainz, Germany
  • M. Basten, M. Busch, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
 
  The FAIR@GSI accelerator facility will require the GSI-UNILAC to provide short heavy ion pulses of highest intensity at low repetition rate for injection into the 18 Tm synchrotron SIS18. However, successful physics programs like SHE (Super Heavy Elements) rely on the UNILAC providing for heavy ion beams of high average current and high duty factor. In the next future, a dedicated super-conducting (sc) cw-Linac should therefore deliver cw beams to the experiments associated with those programs. As a first step towards this goal, beam tests with a single sc Cross-bar H-mode (CH) cavity were successfully conducted in 2017/2018. Within the scope of an Advanced Demonstrator project, current activities now aim at a beam test of a full cryomodule with three sc CH cavities and a sc rebuncher. Given a limited amount of rf power available per cavity and the necessity to accelerate different ion species with different mass-to-charge ratios, the loaded quality factor Q of the different resonators has to be chosen very carefully. This contribution discusses the simulations performed in this context.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP081  
About • paper received ※ 21 June 2019       paper accepted ※ 29 June 2019       issue date ※ 14 August 2019  
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MOP082 Measurement of the Vibration Response of the EXFEL RF Coupler and Comparison With Simulated Data (Finite Element Analyses) 273
 
  • S. Barbanotti, C. Engling, K. Jensch
    DESY, Hamburg, Germany
 
  The coupler is one of the main and most sensitive components of the European X-ray Free Electron Laser (EXFEL) superconducting cryomodule. More than 800 couplers were transported for more than 800 km assembled in a cryomodule during the assembly phase of the EXFEL without any visible damage. However, in a different project, a very similar coupler design showed a week point in one of the bellows when transported over a similar distance with a comparable transport set up. Therefore we decided to further study the coupler behaviour: we investigated the frequency response of the coupler on a vibration table in a controlled environment for different road and loading conditions and compared the data with simulated ones. This paper present the work performed so far and our conclusions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP082  
About • paper received ※ 18 June 2019       paper accepted ※ 29 June 2019       issue date ※ 14 August 2019  
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MOP083 R&D of Copper Electroplating Process for Power Couplers: Effect of Microstructures on RRR 278
 
  • Y. Okii, J. Taguchi
    Nomura Plating Co, Ltd., Osaka, Japan
  • E. Kako, S. Michizono, Y. Yamamoto
    KEK, Ibaraki, Japan
  • H. Takahashi, H. Yasutake
    CETD, Tochigi, Japan
 
  Power couplers for superconducting cavities are required to have both low-thermal conductivity and high-electrical conductivity, because high-thermal conductivity and low-electrical conductivity could generate unexpected increase for heat load. In order to combine these contrary properties, power couplers are made of stainless steel and plated with copper plating. As electrical conductivity of copper layer affects dynamic heat load, it is crucial to optimize plating processes. In this study, we investigated influences of plating parameters (i.e., thickness of copper layer, plating bath composition, bath temperature, heat-treatment conditions) on RRR by collaborative work among Nomura plating, CETD, and KEK. As a result, we obtained high-RRR samples with conditions noted below; (1) electroformed copper plate, (2) copper layer thickness of over 50 µm, and (3) heat-treatment at 200deg-1h, (4) other plating bath composition. In addition, we observed microstructures of several samples, then found that microstructures of copper layer are strongly related to RRR. In this paper, we will present the recent results for this investigation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP083  
About • paper received ※ 23 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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MOP084 A Simple Variable Coupler for the Cryogenic Test of SRF Cavities 282
 
  • G. Ciovati, L. Turlington
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The cryogenic rf tests of SRF cavities in vertical cryostats is typically carried out using fixed-length antennae to couple rf power into the cavity and to probe the energy stored into the cavity. Although variable couplers have been designed, built and used in the past, they are often a complex, costly, not very reliable auxiliary component to the cavity test. In this contribution we present the design and implementation of a simple variable rf antenna which has about 50 mm travel, allowing to obtain about four orders of magnitude variation in Qext -value. The motion of the antenna is driven by a motorized linear feedthrough outside of the cryostat. The antenna can easily be mounted on the most common type of cavity flanges.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP084  
About • paper received ※ 18 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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MOP085 The Destructive Effects to the RF Coupler by the Plasma Discharge 285
 
  • A.D. Wu, Q.W. Chu, H. Guo, Y. He, S.C. Huang, T.C. Jiang, C.L. Li, Z.Q. Lin, F. Pan, Y.K. Song, T. Tan, W.M. Yue, S.H. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People’s Republic of China
 
  The low temperature RF plasma was proved an effec-tive method to clean the niobium surface and relieve the field emission effect for the SRF cavities. In the case of half-wave resonators, these cavities were usually powered via the fundamental coupler with the electric coupling. Thus, coupler antennas were fixed in the intense electric field region, and this region was where the plasma rou-tinely ignited. Therefore, the ceramic window of coupler taken the risk of breakdown under the sputtering of ions and heating loads that may be caused by the plasma drift and diffusion from the electric field region. In this paper, the plasma ignition for surface cleaning on the HWR cavity and its coupler was investigated, and the power transmission, temperature raising and vacuum degradation were tested to characterize the adverse impacts on the ceramic window. Finally, the solution was proposed to figure these issues.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP085  
About • paper received ※ 22 June 2019       paper accepted ※ 02 July 2019       issue date ※ 14 August 2019  
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MOP086 Conditioning of the First Mass Production Power Couplers for the ESS Elliptical Cavities 288
 
  • C. Arcambal, M. Baudrier, P. Bosland, G. Devanz, T. Hamelin, C. Marchand, M. Oublaid, G. Perreu, S. Regnaud, C. Servouin, C. Simon
    CEA-DRF-IRFU, France
  • G. Monnereau
    CEA-IRFU, Gif-sur-Yvette, France
 
  In the framework of the European Spallation Source (ESS), CEA Paris-Saclay is in charge of the delivery of 9 medium beta (β = 0.67) and 21 high beta (β = 0.86) cryomodules. Each cryomodule is composed of 4 cavities equipped with RF (Radio Frequency) power couplers (704.42 MHz, 1.1 MW maximum peak power, repetition rate=14 Hz, RF pulse width > 3.1 ms). Ten prototype power couplers have been manufactured to validate the design and the performance. Currently the mass production of the 120 couplers started and the six first pre-series medium beta couplers have been successfully conditioned. The achievement of this milestone allowed us to launch the production of the remaining 30 medium beta couplers. This paper presents the conditioning of the pre-series couplers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP086  
About • paper received ※ 23 June 2019       paper accepted ※ 29 June 2019       issue date ※ 14 August 2019  
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WETEB8 The Fundamental Power Coupler for CEPC Booster Cavity 789
 
  • T.M. Huang, F. Bing, R. Guo, H.Y. Lin, Q. Ma, W.M. Pan, J.Y. Zhai, Z. Zhang
    IHEP, Beijing, People’s Republic of China
 
  Funding: Supported by National natural Science Foundation of China ( 11475203)
96 Tesla type 1.3GHz 9-cell superconducting cavities, housed in eight 12m-long cryomodules, will be adopted for CEPC booster. Each cavity equips with one variable coupling, double-window fundamental power coupler (FPC). The FPC will operate at RF power up to 20 kW at quasi-CW mode. A variable coupling from 4·106 to 107 is required to meet different operation modes of Higgs, W and Z. A new coupler that employs a 50 Ω coaxial line with bellow structures, a cylindrical warm window, a coaxial planar cold window and a coupling adjusting actuator has been designed. Then two prototypes have been fabricated and high power tested up to CW 70 kW successfully. In this paper, the design, fabrication and high power test of the prototype FPCs will be presented.
 
slides icon Slides WETEB8 [9.971 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEB8  
About • paper received ※ 23 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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WETEB9 Design Development for the 1.5 GHz Couplers for BESSY VSR 795
 
  • E. Sharples, M. Dirsat, J. Knobloch, Z. Muza, A.V. Vélez
    HZB, Berlin, Germany
 
  The Variable pulse length Storage Ring (BESSY VSR) is a superconducting radio frequency (SRF) upgrade to the existing BESSY II storage ring at Helmholtz-Zentrum Berlin (HZB). BESSY VSR uses the RF beating of superconducting cavities at 1.5 GHz and 1.75 GHz to produce simultaneously long and short bunches. Higher power couplers capable of handling 13 kW peak power at standing wave operation, are required to provide an average power of 1.5 kW for both the 1.5 GHz and 1.75 GHz cavities. These couplers must also provide variable coupling with a range of Qext from 6x106 to 6x107 to allow flexibility to adjust to operating conditions of BESSY VSR. Here the full design development process for the 1.5 GHZ BESSY VSR coupler is presented including the design for a diagnostic prototype to ensure comprehensive monitoring of critical components during testing and cool-down.  
slides icon Slides WETEB9 [8.085 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEB9  
About • paper received ※ 23 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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