Keyword: HOM
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MOIOA03 The Challenge and Realization of the Cavity Production and Treatment in Industry for the European XFEL cavity, niobium, controls, superconductivity 18
 
  • W. Singer, J. Iversen, A. Matheisen, H. Weise
    DESY, Hamburg, Germany
  • P. Michelato
    INFN/LASA, Segrate (MI), Italy
  
  The main effort in production of 1.3 GHz cavities for the EXFEL was dedicated to transfer the superconducting technology to the industry. These know how transfer is executed by DESY and INFN/LASA team. The preparation phase based on prototype cavities covered: qualification of potential vendors for material and cavity fabrication; work out recipe and strategy for qualification of the infrastructure for cavity surface treatment at industry; definition of the quality management strategy, documentation and electronically data exchange. Production of 800 series cavities on the principle “build to print” is contracted to companies Research Instruments and Ettore Zanon. High purity niobium and NbTi for resonators provides DESY. The principles of the material and cavities production in conformity with European Pressure Equipment Directive are developed together with the notified body. New or upgraded infrastructure has been established at both companies. The first several tens of series cavities have been produced and treated. Most of the cavities handed over to DESY up to now fulfill immediately the EXFEL specifications. The cavity production for EXFEL will be finished mid of 2015.  
slides icon Slides MOIOA03 [7.394 MB]  
 
MOIOA04 SRF Challenges for Energy Recovery Linacs cavity, SRF, linac, operation 24
 
  • A. Burrill
    HZB, Berlin, Germany
  
  Many of the challenges associated with operating a SRF ERL are independent of the choice of operating frequency, beam energy, and overall purpose of the machine. Worldwide there are an increasing number of ERLs in various stages of development and operation which are facing a number of similar challenges and often solving them in very different ways. In this talk I will seek to summarize the main challenges the community as a whole faces, address how different laboratories are working to solve these problems, and seek to identify areas of overlap where the community can work together to solve some of these common problems.  
slides icon Slides MOIOA04 [5.213 MB]  
 
MOP011 European XFEL 3.9 GHz System cavity, linac, cryomodule, controls 100
 
  • P. Pierini, M. Bertucci, A. Bosotti, C. Maiano, P. Michelato, L. Monaco, R. Paparella, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  • E. Vogel
    DESY, Hamburg, Germany
  
  The third harmonic system of the European XFEL is a joint INFN and DESY contribution to the project. Achievements, status and activity plan will be reviewed.  
 
MOP022 Preliminary Design of CEPC RF Superconducting System cavity, impedance, cryogenics, storage-ring 140
 
  • H.J. Zheng, J. Gao, S. Jin, Y. Liu, Z.C. Liu, J.Y. Zhai, T.X. Zhao
    IHEP, Beijing, People's Republic of China
  
  In order to study Higgs Boson, scientists proposed to construct a Higgs factory. Chinese scientists are also actively involved in research of the construction of Higgs factory. Construction of a circular collider and several construction solutions were proposed. Electron and positron are eventually accelerated to the center of mass energy 240GeV. RF superconducting acceleration system is indispensable to ensure the normal operation of machine. This article mainly introduces the RF parameters in the design of 700MHz China Higgs Factory (CHF) system. It mainly includes choose of cavity type, couplers and relevant parameters of cryogenic system.  
 
MOP037 Test of the 1.3 GHz Superconducting Cavities for the European X-ray Free Electron Laser cavity, vacuum, software, pick-up 191
 
  • K. Krzysik
    DESY, Hamburg, Germany
  • B. Dzieza, W. Gaj, D. Karolczyk, K. Kasprzak, L.M. Kolwicz-Chodak, A. Kotarba, A. Krawczyk, W. Maciocha, A. Marendziak, K. Myalski, S. Myalski, T. Ostrowicz, B. Prochal, M. Sienkiewicz, M. Skiba, J. Świerbleski, M. Wiencek, J. Zbroja, A. Zwozniak
    IFJ-PAN, Kraków, Poland
  
  The European X-ray Free Electron Laser (XFEL) is currently under construction in Germany in Hamburg area. A linear accelerating part of the XFEL is going to consist of 808 superconducting 9-cell Niobium cavities installed in 101 accelerating modules. Before assembly into modules the cavities are tested in a dedicated test facilities. The testing procedures are prepared based on DESY expertise and available software from Tesla Test Facility (TTF) Collaboration and Free electron LASer for Hamburg (FLASH). RF test provides the most important information about cavity performance: maximum available gradient and dependence of quality factor and radiation on the gradient. Results of the RF test determine, whether a cavity is shipped to CEA Saclay (France) to be assembled into a module or send for retreatment to improve its performance. In this paper we present the most important aspects of the cavity RF test procedure.  
 
MOP055 Status of the Superconducting Cavity Development for ILC cavity, cryomodule, status, linac 247
 
  • T. Yanagisawa, H. Hara, F. Inoue, K. Kanaoka, K. Sennyu
    MHI, Hiroshima, Japan
  
  MHI activities for ILC are reported. MHI had developed several procedure and method of cavity production for stable quality and cost reduction. And we are producing cryomodules too. These activities are reported in detail.  
 
MOP061 75 mA Operation of the Cornell ERL Superconducting RF Injector Cryomodule operation, SRF, cryomodule, cavity 259
 
  • M. Liepe, B.M. Dunham, R.G. Eichhorn, G.H. Hoffstaetter, R.P.K. Kaplan, P. Quigley, E.N. Smith, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: This work is supported by the National Science Foundation (Grant No. DMR-0807731).
Cornell University has developed a SCRF injector cryomodule for the acceleration of high current, low emittance beams in continuous wave operation. This cryomodule is based on 1.3 GHz superconducting RF technology, and has been tested extensively in the Cornell ERL injector prototype with world record CW beam currents exceeding 70 mA. High CW RF power input couplers and strong Higher-Order-Mode damping in the cavities are essential for high beam current operation. This paper summarizes the performance of the cryomodule during the high beam current operation. 		 
 
MOP064 Operational Experience with the SOLEIL Superconducting RF System cavity, cryogenics, operation, vacuum 269
 
  • P. Marchand, J.P. Baete, R.C. Cuoq, H.D. Dias, M. Diop, J.L. Labelle, R. Lopes, M. Louvet, C.M. Monnot, S. Petit, F. Ribeiro, T. Ruan, R. Sreedharan, K. Tavakoli
    SOLEIL, Gif-sur-Yvette, France
  
  In the SOLEIL storage ring, two cryomodules provide to the electron beam an accelerating voltage of 3-4 MV and a power of 575 kW at 352 MHz. Each cryomodule contains a pair of superconducting cavities, cooled with liquid Helium at 4K, which is supplied by a single 350 W cryogenic plant. The RF power is provided by 4 solid state amplifiers, each delivering up to 180 kW. The parasitic impedances of the high order modes are strongly mitigated by means of four coaxial couplers, located on the central pipe connecting the two cavities. Seven years of operational experience with this system as well as its upgrades are reported.  
 
MOP073 IHEP 1.3 GHz Low Loss Large Grain 9-cell Cavity Fabrication, Processing and Test cavity, SRF, vacuum, niobium 305
 
  • J.Y. Zhai, J. Gao, S. Jin, Z.Q. Li, Y. Liu, Z.C. Liu, Z.H. Mi, X.H. Peng, T.X. Zhao, H.J. Zheng
    IHEP, Beijing, People's Republic of China
  • C.A. Cooper, C.M. Ginsburg, T.N. Khabiboulline, A.M. Rowe, D.A. Sergatskov
    Fermilab, Batavia, USA
  • J.X. Wang, H. Yu, H. Yuan
    BIAM, Beijing, People's Republic of China
  
  The combination of the low-loss shape and large grain niobium material is expected to be the possible way to achieve higher gradient and lower cost for ILC 9-cell cavities, and will be essential for the ILC 1 TeV upgrade. As the key component of the “IHEP 1.3 GHz SRF Accelerating Unit Project”, a low-loss shape 9-cell cavity with full end groups using Ningxia large grain niobium (IHEP-02) was fabricated at IHEP in 2012. The cavity was processed (CBP and EP) and tested at FNAL. The cavity processing,test performance and gradient limitation is reported in this paper. We will weld the helium vessel, assemble the magnetic shield and install the cavity to IHEP ILC-TC1 cryomodule.  
 
MOP077 Cryomodule Component Development for the APS Upgrade Short Pulse X-Ray Project cavity, cryomodule, vacuum, alignment 314
 
  • J.P. Holzbauer, J.D. Fuerst, A. Nassiri, Y. Shiroyanagi, B.K. Stillwell, G.J. Waldschmidt, G. Wu
    ANL, Argonne, USA
  • G. Cheng, J. Henry, J.D. Mammosser, J. Matalevich, J.P. Preble, R.A. Rimmer, H. Wang, K.M. Wilson, M. Wiseman, S. Yang
    JLAB, Newport News, Virginia, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357 at ANL and under U.S. DOE Contract No. DE-AC05-06OR23177 at Jefferson Lab.
The short pulse x-ray (SPX) part of the Advanced Photon Source Upgrade calls for the installation of a two-cavity cryomodule in the APS ring to study cavity-beam interaction, including HOM damping and cavity timing and synchronization. Design of this cryomodule is underway at Jefferson Lab in collaboration with the APS Upgrade team at ANL. The cryomodule design faces several challenges including tight spacing to fit in the APS ring, a complex set of cavity waveguides including HOM waveguides and dampers enclosed in the insulating vacuum space, and tight alignment tolerances due to the APS high beam-current (up to 150 mA). Given these constraints, special focus has been put on modifying existing CEBAF-style designs, including a cavity tuner and alignment scheme, to accommodate these challenges. The thermal design has also required extensive work including coupled thermal-mechanical simulations to determine the effects of cool-down on both alignment and waveguides. This work will be presented and discussed in this paper. 		 
 
MOP083 Operational Experience With the SOLEIL Storage Ring RF Cryogenic Plant cryogenics, controls, operation, cavity 337
 
  • M. Louvet, H.D. Dias, M. Diop, P. Marchand
    SOLEIL, Gif-sur-Yvette, France
  
  In the Storage Ring of the Synchrotron SOLEIL light source, two cryomodules provide the required power of 575 kW at the nominal energy of 2.75 GeV with the full beam current of 500 mA and all the insertion devices. Each cryomodule contains a pair of 352 MHz superconducting cavities (Nb/Cu), cooled in a bath of liquid helium at 4.5 K. A single 350 W cryogenic system supplies the liquid helium for the two cryomodules. The seven years of operational experience with this cryogenic plant as well as its upgrades are reported.  
 
MOP086 Integration, Commissioning and Cryogenics Performance of the ERL Cryomodule Installed on ALICE-ERL Facility at STFC Daresbury Laboratory, UK cryomodule, cryogenics, SRF, linac 349
 
  • S.M. Pattalwar, R.K. Buckley, P.A. Corlett, P. Goudket, A.R. Goulden, A.J. May, P.A. McIntosh, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S.A. Belomestnykh
    BNL, Upton, Long Island, New York, USA
  • A. Büchner, F.G. Gabriel, P. Michel
    HZDR, Dresden, Germany
  • E.P. Chojnacki, J.V. Conway, R.G. Eichhorn, G.H. Hoffstaetter, M. Liepe, H. Padamsee, P. Quigley, J. Sears, V.D. Shemelin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • M.A. Cordwell, T.J. Jones, L. Ma, A.J. Moss, J. Strachan
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • J.N. Corlett, D. Li, S.M. Lidia
    LBNL, Berkeley, California, USA
  • T. Kimura
    Stanford University, Stanford, California, USA
  • R.E. Laxdal
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  • J.K. Sekutowicz
    DESY, Hamburg, Germany
  • T.J. Smith
    SLAC, Menlo Park, California, USA
  
  On successful assembly and preliminary testing of an optimised SRF cryomodule for application on ERL accelerators, which is being developed through an international collaboration the cryomodule has been installed on the 35 MeV ALICE (Accelerators and Lasers in Combined Experiments) Energy Recovery Linac (ERL) facility at STFC Daresbury Laboratory. Existing cryogenic infrastructure has a capacity to deliver approximately 120 W cooling power at 2 K, but the HOM (Higher Order Mode) absorbers, the thermal intercepts for the high power RF couplers and the radiation shield in the cryomodule are designed to be cooled (to 5 K and 80 K) with gaseous helium instead of liquid nitrogen. As a result the cryogenic infrastructure for ALICE had to be modified to meet these additional requirements. In this paper we describe our experience with the process of integration and the cryogenic commissioning, and present some initial results.  
 
MOP092 Computation of Wakefields and HOM Port Signals by Means of Reduced Order Models wakefield, impedance, cavity, operation 364
 
  • J. Heller, T. Flisgen, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  
  The investigation of wakefields is an important task in the design and operation of particle accelerators. Computer simulations are a reliable tool to extend the understanding of these effects. This contribution presents an application example of a new method to compute wakefields as well as parameters derived from those fields, such as higher order mode (HOM) port signals. The method is based on a reduced order model of the structure created by as set of 3D eigenmodes, a set of 2D waveguide port modes and the current density of the beam. In contrast to other wakefield computations, the proposed method operates directly on the reduced order model. Therefore, once having established this model, the beam-excited fields can be determined quickly for different beam parameters. As a matter of fact, only a small part of the reduced system has to be recomputed for every sweep point. From these advantages it is obvious, that the method is highly compatible for beam parameter studies. In a proof of principal the effectiveness of the method compared to established methods of wakefield computations in terms of computational time and accuracy is shown.  
 
MOP093 Geometric Optics of Wake Fields of Very Short Bunches in Superconducting Cavities cavity, wakefield, FEL, superconducting-cavity 367
 
  • A. Novokhatski
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by Department of Energy contract DE-AC02-76SF00515
We study the wake potentials of very short bunches in a quasi periodic structure of superconducting cavities. We analyze the pattern of the electric force lines and the shape of a cavity. The behavior of electric force lines reflects irregularities of the shape structure of a cavity. Simulations were carried for different kind of cavities, including JLAB 7 cell cavity with application to future light sources. 		 
 
TUP082 Materials Analysis of CED Nb Films Being Coated on Bulk Nb Single Cell SRF Cavities cavity, SRF, ion, cryogenics 638
 
  • X. Zhao, C.E. Reece
    JLab, Newport News, Virginia, USA
  • G. Ciovati
    Jefferson Lab, Newport News, Virginia, USA
  • I. Irfan, C. James, M. Krishnan
    AASC, San Leandro, California, USA
  • A.D. Palczewski
    JLAB, Newport News, Virginia, USA
  
  Funding: This research is supported at AASC by DOE via Grant No. DE-FG02-08ER85162 and Grant No. DE-SC0004994 and by Jefferson Science Associates, LLC under U.S. DOE Contract No. DEAC05- 06OR23177
This study is an on-going research on depositing a Nb film on the internal wall of bulk Nb single cell SRF cavities, via an coaxial energetic condensation (CED) facility at AASC company. The motivation is to firstly create a homoepitaxy-like Nb/Nb film in a scale of a ~1.5GHz RF single cell cavity. Next, through SRF measurement and materials analysis, it might reveal the baseline properties of the CED-type homoepitaxy Nb films. Such knowledge of Nb-Nb homo-epitaxy is useful to create future realistic SRF cavity film coatings, such as hetero-epitaxy Nb/Cu Films, or template-layer-mitigated Nb films. One large-grain, and three fine grain bulk Nb cavity were coated. They went through cryogenic RF measurement. Preliminary results show that the Q0 of a Nb film at 2 K and low rf field, produced by CED, could be close to that of the pre-coated bulk Nb surface (being CBP'ed plus a light EP); but the quality drops rapidly for increasing rf field. We are investigating if the severe Q0-slope is caused by hydrogen incorporation before deposition, or is determined by some structural defects during Nb film growth. 		 
 
TUP096 High Power Processing at a High Order Mode Frequency cavity, gun, SRF, cathode 697
 
  • V. Volkov
    BINP SB RAS, Novosibirsk, Russia
  • J. Knobloch, A.N. Matveenko, A. Neumann
    HZB, Berlin, Germany
  
  Regular High Power Processing (HPP) at fundamental frequency in a superconducting cavity usually carried out to increase maximal RF field in the cavity that is limited by Field Emission (FE). HPP at a High Order Mode (HOM) frequency allow significantly increasing FE threshold of fundamental RF field. In the paper we give proof of this prediction and give the concrete proposal of such HPP design for Rossendorf 3.5-cell RF gun structure. Expected RF over field is about 100% (from 17 up to 34 MV/m) as compared with a regular HPP.  
 
THIOA03 Cavity Fabrication Study in CFF at KEK cavity, niobium, electron, gun 821
 
  • M. Yamanaka, Y. Ajima, H. Inoue, T. Kubo, T. Saeki, Y. Watanabe, S. Yamaguchi
    KEK, Ibaraki, Japan
  
  The construction of new facility for the fabrication of superconducting RF cavity at KEK was completed in 2011. It is equipped with the following machines; an electron-beam welding (EBW) machine, a servo press machine and a CNC vertical lathe. A chemical etching apparatus is also equipped. The study on the fabrication of 9-cell cavity for International Linear Collier (ILC) has been started from 2009 using this facility. The study is focusing on the cost reduction with keeping high performance of cavity, and the goal is the establishment of mass-production procedure for ILC.  
slides icon Slides THIOA03 [7.823 MB]  
 
THIOB02 High Q Cavities for the Cornell ERL Main Linac cavity, linac, cryomodule, SRF 844
 
  • R.G. Eichhorn, B. Bullock, B. Clasby, B. Elmore, F. Furuta, A. Ganshin, G.M. Ge, D. Gonnella, D.L. Hall, Y. He, K.M.V. Ho, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V.D. Shemelin, E.N. Smith, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  While SRF research for linear colliders was focused on achieving high gradients, Cornell’s proposal for an energy recovery linac (ERL) demanded for low cw losses. Starting several years ago, a high-Q R&D phase was launched that led to remarkable results recently: A fully dressed cavity (7 cells, 1.3 GHz) with side-mounted input coupler and beamline HOM absorbers achieved a Q of 3.5·1010 ((16 MV/m, 1.8 K). This talk will review the staged approach we have chosen in testing a single cavity in a horizontal short cryomodule (HTC), report results on each step and conclude on our findings about preserving high Q from vertical testing. We also discuss the production of six additional cavities as we progress toward constructing a full 6-cavity cryomodule as a prototype for Cornell’s main linac module  
slides icon Slides THIOB02 [8.378 MB]  
 
THIOC02 High Power CW Tests of cERL Main-Linac Cryomodule cryomodule, cavity, linac, alignment 855
 
  • H. Sakai, K. Enami, T. Furuya, M. Satoh, K. Shinoe, K. Umemori
    KEK, Ibaraki, Japan
  • E. Cenni
    Sokendai, Ibaraki, Japan
  • M. Sawamura
    JAEA, Ibaraki-ken, Japan
  
  A main linac cryomodule have been constructed for Compact ERL project. It contains two 9-cell cavities, mounted with HOM absorbers and input couplers. After cavity string assembly, they were installed into the vacuum vessel of the cryomodule. It was placed inside radiation shield of cERL and connected to a refrigerator system. The cryomodule was successfully cooled down to 2K and low power and high power measurements were carried out.  
slides icon Slides THIOC02 [12.842 MB]  
 
THIOC03 Superconducting Photonic Band Gap Structures for High-Current Applications cavity, SRF, accelerating-gradient, wakefield 860
 
  • E.I. Simakov, S. Arsenyev, W.B. Haynes, S.S. Kurennoy, D.Y. Shchegolkov, N.A. Suvorova, T. Tajima
    LANL, Los Alamos, New Mexico, USA
  • C.H. Boulware, T.L. Grimm
    Niowave, Inc., Lansing, Michigan, USA
  
  Funding: This work is supported in parts by the U.S. DOE Early Career Research Program and by the DOD High Energy Laser Joint Technology Office through the Office of Naval Research.
We present the results of recent design and testing of several 2.1 GHz superconducting rf (SRF) photonic band gap (PBG) resonators. PBG cells have great potential for outcoupling long-range wakefields in SRF accelerator structures without affecting the fundamental accelerating mode. Using PBG structures in superconducting particle accelerators will allow operation at higher frequencies and moving forward to significantly higher beam luminosities thus leading towards a completely new generation of colliders for high energy physics. Here we report the results of our efforts to fabricate 2.1 GHz PBG cells with round and elliptical rods and to test them with high power at liquid helium temperatures. Two PBG cells with round rods were tested in spring of 2012 and achieved accelerating gradients of 15 MV/m at 2 Kelvin. Two PBG cells with elliptical rods will be tested in summer of 2013. 		 
slides icon Slides THIOC03 [2.284 MB]  
 
THP001 Development of a Prototype SRF Cavity for the Proton Beam Utilization Facility at Nanjing University cavity, SRF, proton, linac 889
 
  • S. An, P.P. Xue
    PLAI, Nanjing, People's Republic of China
  • S.Q.X. Xu, H. Z. Zhang
    ADS-SRF, People's Republic of China
  • P.P. Xue, L. Zhang
    Chang’an University, Chang'an, People's Republic of China
  • Z.R. Zhang
    Nanjing University of Aeronautics and Astronautics, Jiangning, People's Republic of China
  
  Nanjing University has initiated the new technology development in the field of high-energy, charged-particle beam application and fundamental sciences. A high-current proton accelerator used for the new energy, new technology and fundamental science applications platform will be the near term goal at Nanjing University. For developing the superconducting RF linac for the proton beam utilization at Nanjing University, the first 6-cell, medium-beta prototype superconducting RF cavity has been fabricated and demonstrated using Chinese vendors only. The low-power test has been completed. The vertical test will be carried out soon.  
 
THP019 1.3 GHz SRF Cavity Tests for ARIEL at TRIUMF cavity, TRIUMF, linac, SRF 933
 
  • P. Kolb, P.R. Harmer, D. Kishi, A. Koveshnikov, C. Laforge, D. Lang, R.E. Laxdal, Y. Ma, B.S. Waraich, Z.Y. Yao, V. Zvyagintsev
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  
  The 1.3 GHz cavity test program at TRIUMF for the ARIEL eLINAC progressed into its next stage: Going from single cell cavity tests to demonstrate the operating Q and gradient for ARIEL can be reached at TRIUMF to nine cell cavity tests for production cavities. Single cell cavity tests at TRIUMF showed a comparable performance to a characterization done on the same cavity at FNAL last year. These single cell tests showed that the operating point for ARIEL of Q0 > 1010 at 10 MV/m during 2 K operation can be reached and exceeded at TRIUMF. To prepare for the first ARIEL nine cell cavity, a test with a TESLA nine cell cavity was done. This included frequency and field tuning, etching via BCP, HPR and assembly in a class 10 clean environment as well as modifications to the cryo assembly and upgrades to the 2 K pumping system. The performance of this TESLA cavity and the performance of first ARIEL nine cell cavity produced by PAVAC will be shown.  
 
THP020 Measuring the Higher Order Mode Spectrum of the TRIUMF 9-cell Cavity cavity, dipole, TRIUMF, simulation 936
 
  • P. Kolb, B. Amini, R.E. Laxdal, Y. Ma, Z.Y. Yao, V. Zvyagintsev
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  
  The ARIEL eLINAC consists of five nine cell cavities, produced by PAVAC, and will accelerate 10 mA electrons to 50 MeV. This 500 kW beam will be used for rare isotope production. Future upgrade plans include a recirculating beam line. Recirculating the beam, for either energy doubling or energy recovery to drive a FEL, brings the risk of multi-pass beam break up (BBU). Therefore it is necessary to avoid higher order modes (HOMs) with high shunt impedance. The goal of the cavity design is to reduce the highest shunt impedance of any dipole HOM to 1 *106Ω or less. Measurements on the nine cell cavity with bead pulling have been done to identify dipole modes and their geometric shunt impedance R/Q as well as measurements at 2 K to estimate the quality factor of those HOMs. Results of these measurements will be shown and compared to computer simulations done with ACE3P.  
 
THP026 Cage Cavity: A Low Cost, High Performance SRF Accelerating Structure cavity, SRF, vacuum, simulation 950
 
  • J. Noonan, T.L. Smith, M. Virgo, G.J. Waldschmidt
    ANL, Argonne, USA
  • J.W. Lewellen
    LANL, Los Alamos, New Mexico, USA
  
  Funding: Funded by Office of Naval Research. Argonne National Laboratory is operated by UChicago-Argonne LLC for the Department of Energy
The Cage Cavity is a new SRF cavity technology using tubes formed into the shape of a solid wall cavity then assembled into a closed volume. The theory is that the cage cavity will form a resonant cavity at RF frequencies below a critical frequency at which the cage structure behaves as a solid structure. Several cage cavity structures have been fabricated and measured that demonstrate good RF properties. Comparison of simulations and measurements for these structures will be discussed. More importantly, simulations have identified a new cage cavity configuration in which an SRF cage cavity’s quality factor is greater than 10exp10. The cage cavity must operate in a vacuum vessel which is also an RF cavity. By choosing the cage cavity resonant frequency to be decoupled from the vessel higher order resonances, simulations show that the cage cavity Q is ~95% of a solid wall SRF cavity. The Cage Cavity design, fabrication costs, and high order mode behavior have a number of advantages over solid wall cavities. However, the cage cavity also has limitations. The design and properties of the cage cavity will be discussed and compared with existing SRF cavities. 		 
 
THP036 Design of a 4 Rod Crab Cavity Cryomodule System for HL-LHC cavity, cryomodule, luminosity, impedance 982
 
  • G. Burt, B.D.S. Hall
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • T.J. Jones, N. Templeton
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • P.A. McIntosh, S.M. Pattalwar, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • T.J. Peterson
    Fermilab, Batavia, USA
  • L.A. Wright
    CERN, Geneva, Switzerland
  
  The LHC requires compact SRF crab cavities for the HL-LHC and 3 potential solutions are under consideration. One option is to develop a 4 rod cavity utilising for quarter wave rods to maintain a dipole field. The cavity design has been developed including power and LOM/HOM couplers have been developed, as well as a conceptual design of a complete cryomodule system including ancillaries and this is presented. The cryomodule is designed to allow easy access during testing and uses a novel support system and contains the opposing beamline section to fit inside the LHC envelope.  
 
THP041 Optimization of the Double Quarter Wave Crab Cavity Prototype for Testing at SPS cavity, interface, acceleration, luminosity 995
 
  • S. Verdú-Andrés, S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu, B. P. Xiao
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  • R. Calaga
    CERN, Geneva, Switzerland
  • Z. Li
    SLAC, Menlo Park, California, USA
  
  Funding: Research supported by EU FP7 HiLumi LHC – No. 284404, and by US DOE through Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 and the US LHC Accelerator Research Program (LARP).
The crab cavity program for LHC luminosity upgrade envisages the testing of at least one of the three competing crab cavities in the Super Proton Synchrotron (SPS) of CERN by 2016. This paper presents the design optimization of a Double Quarter Wave Crab Cavity (DQWCC) prototype suited for testing in SPS. 		 
 
THP042 High Frequency SRF Cavity Study for Bunch Shortening in PEPX cavity, SRF, FEL, simulation 998
 
  • L. Xiao, K.L.F. Bane, Y. Cai, X. Huang, C.-K. Ng, A. Novokhatski, L. Wang
    SLAC, Menlo Park, California, USA
  
  The proposed PEPX is a diffraction limited storage ring light source, or “ultimate storage ring (USR)”, which can be built in the PEP tunnel at SLAC. The 4.5GeV PEPX design based on the USR with a natural emittance about 10pm-rad can be used to drive a high-gain soft X-ray FEL. In order to achieve a desired high peak current over 300A for the FEL, the bunch length is reduced to 1ps from 10ps through a set of multi-cell SRF cavities working at 1.428GHz in CW mode, providing about 300MV RF gradient. In this paper, the 1.5GHz JLAB C100 cavity for the CEBAF upgrade and 1.3GHz Cornell ERL cavity are investigated for its application to PEPX-FEL. The simulation results show that the beam induced high order modes (HOM) in the C100 cavities will limit the threshold of the beam current for PEPX-FEL. And the same pass band modes (SPM) in the cavities are strongly trapped, and thus generate unacceptable beam power once they hit the beam resonances. Therefore, a 5-cell with a larger iris cavity design instead of the C100 7-cell design is proposed. Preliminary results on the rf parameters of the cavity, HOM damping and beam dynamics studies will be presented.  
 
THP043 Design and Vertical Test of Double Quarter Wave Crab Cavity for LHC Luminosity Upgrade cavity, cryogenics, simulation, pick-up 1002
 
  • B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, R. Calaga, C. Cullen, L.R. Hammons, J. Skaritka, S. Verdú-Andrés, Q. Wu
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  
  Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with LARP and the U.S. DOE, and supported by EU FP7 HiLumi LHC - Grant Agreement 284404.
A proof of principle Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. Vertical cryogenic test has been done in Brookhaven National Lab (BNL). We report the test results of this design. 		 
 
THP044 Compact Higher Order Mode Filter for Crab Cavities in the Large Hadron Collider cavity, luminosity, simulation, cryomodule 1006
 
  • B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, S. Verdú-Andrés, Q. Wu
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  • R. Calaga
    CERN, Geneva, Switzerland
  
  Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with LARP and the U.S. DOE, and supported by EU FP7 HiLumi LHC - Grant Agreement 284404.
A double quarter wave crab cavity was designed for the Large Hadron Collider luminosity upgrade. Starting from the analytical calculation of simplified RLC circuit, a compact higher order mode filter is developed for this cavity. Finite element simulation results are presented. The design concept is generic and can easily be adapted to other cavities. 		 
 
THP048 The Influence of Tuners and Temperature on the Higher Order Mode Spectrum for 1.3 GHz SCRF Cavities cavity, quadrupole, dipole, higher-order-mode 1016
 
  • R. Ainsworth
    Royal Holloway, University of London, Surrey, United Kingdom
  • N. Baboi, M.K. Grecki, T. Wamsat
    DESY, Hamburg, Germany
  • N. Eddy
    Fermilab, Batavia, USA
  • S. Molloy
    ESS, Lund, Sweden
  • P. Zhang
    CERN, Geneva, Switzerland
  
  Higher Order Modes are of concern for superconducting cavities as they can drive instabilities and so are usually damped and monitored. With special dedicated electronics, HOMs can provide information on the position on the beam. It has been proposed that piezo tuners used to keep the cavities operating at 1.3 GHz could alter the HOM spectrum altering the calibration constants used to read out the beam position affecting long term stability of the system. Also, of interest is how the cavity reacts to the slow tuner. Detuning and the retuning the cavity may alter the HOM spectrum. This is of particular interest for future machines not planning to use dedicated HOM damping as the tuning procedure may shift the frequency of HOMs onto dangerous resonances. The effect of temperature on the HOM spectrum is also investigated. An investigation of these effects has been performed at FLASH and the results are presented including numerical simulations used to predict the resulting cavity distortion.  
 
THP052 Cornell’s Beam Line Higher Order Mode Absorbers linac, vacuum, cryomodule, damping 1027
 
  • R.G. Eichhorn, J.V. Conway, Y. He, Y. Li, T.I. O'Connel, P. Quigley, J. Sears, N.R.A. Valles
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • V.D. Shemelin
    Cornell University, Ithaca, New York, USA
  
  Efficient damping of the higher-order modes (HOMs) of the superconducting cavities is essential for the proposed energy recovery linac at Cornell that aims for high beam currents and short bunches. Designing these HOM beamline absorbers has been a long endeavor, sometimes including disappointing results. We will review the design, the findings on the prototype and the final choices made for the 7 HOM absorbers being built for the main linac cryomodule (MLC) prototype.  
 
THP055 Ferrite Covered Ceramic Break HOM Damper cavity, gun, vacuum, damping 1040
 
  • H. Hahn, S.A. Belomestnykh, I. Ben-Zvi, L.R. Hammons, V. Litvinenko, R.J. Todd, D. Weiss, W. Xu
    BNL, Upton, Long Island, New York, USA
  • A. Burrill
    HZB, Berlin, Germany
  • J. Dai
    Stony Brook University, Stony Brook, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under contract no. DE-AC02-98CH10886 with the DOE.
The Brookhaven Energy Recovery Linac (ERL) is operated as R&D setup for high-current, high charge electron beams. It is comprised of a superconducting (SC) five-cell cavity and a half-cell SC photoinjector electron RF gun. Achieving the performance objectives requires effective HOM damping in the linac and gun cavity. Among the HOM dampers being developed is a beam-tube type HOM load for the electron gun consisting of a ceramic break surrounded by ferrite tiles. This design is innovative in its approach and achieves a variety of ends including broadband HOM damping and protection of the superconducting cavity from potential damage of the separately cooled ferrite tiles. The damper properties are described by the coupling impedance to a beam and the external Q to constrain the unloaded mode Q’s. Measured results for the gun damper at room and superconducting temperatures are presented 		 
 
THP059 HOM Coupler Design Adjustment for CW operation of the 1.3 GHz 9-cell TESLA Type SRF Cavity dipole, cavity, operation, simulation 1051
 
  • D. Kostin, W.-D. Möller, J.K. Sekutowicz
    DESY, Hamburg, Germany
  
  One of the key features of a modern research facility is its versatility, ability to adjust for a multitude of the applications and user needs. A challenge for the coming European XFEL is to become a multipurpose laboratory with a broad applications spectrum. Primarily, the XFEL is a pulsed machine. Encompassing the CW mode would be a worthy addition. CW operation of the 1.3GHz 9-cell TESLA Type SRF Cavity was performed several times at DESY and other Labs successfully. One of the difficulties was a heat load of the High Order Mode (HOM) couplers. To amend this HOM coupler design adjustement is proposed, simulated and modelled. Results are presented and discussed.  
 
THP061 Developments of HOM Dampers for SuperKEKB Superconducting Cavity cavity, simulation, operation, factory 1058
 
  • M. Nishiwaki, K. Akai, T. Furuya, A. Kabe, S. Mitsunobu, Y. Morita
    KEK, Ibaraki, Japan
  
  Eight superconducting accelerating cavities were stably operated under a high beam current and a large beam induced HOM power in KEKB electron ring. The HOM power of 16 kW at the beam current of 1.4A was absorbed in two ferrite dampers attached to each cavity. In SuperKEKB, that is the upgrade machine of KEKB, the design beam current is 2.60 A. The HOM power of higher than 40 kW is expected to be induced. To cope with the large HOM power, precise evaluations of HOM power loads including HOM dampers were carried out. Then, new ferrite dampers with reinforced water cooling were developed and high-power tested. On the other hand, the evaluation indicated that an additional HOM damper can absorb significant amount of HOM power. Additional damper is effective to reduce each ferrite damper load. In this report, we will describe the results of high power tests of the new ferrite dampers, studies for additional dampers, and an installation plan for SuperKEKB.  
 
THP064 HOM Couplers for CERN SPL Cavities coupling, cavity, dipole, linac 1066
 
  • K. Papke, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • F. Gerigk
    CERN, Geneva, Switzerland
  
  Funding: Work supported by the Wolfgang-Gentner-Programme of the Bundesministerium für Bildung und Forschung (BMBF)
Higher-Order-Modes (HOMs) may affect beam stability and refrigeration requirements of superconducting proton linacs such as the SPL, which is studied at CERN as the driver for future neutrino facilities. In order to limit beam-induced HOM effects CERN considers the use of HOM couplers on the cut-off tubes of the 5-cell superconducting cavities. These couplers consist of resonant antennas shaped as loops or probes which are designed to couple to modes of a specific frequency range. In this paper the design process is presented and a comparison is made between various design options for the medium and high-beta SPL cavities, both operating at 704 MHz. The RF characteristics, thermal behaviour and multipacting sensitivity of the various designs are discussed and 2 options are presented, which will be tested as warm prototypes on 5-cell high-beta copper cavity models. 		 
 
THP068 New Design of HOM Coupler Using Coaxial-like Rounded Waveguide cavity, damping, simulation, operation 1081
 
  • M. Sawamura
    Japan Atomic Energy Agency (JAEA), Gamma-ray Non-Destructive Assay Research Group, Tokai-mura, Ibaraki-ken, Japan
  • R. Hajima, R. Nagai, N. Nishimori
    JAEA, Ibaraki-ken, Japan
  
  It is important to damp higher-order modes (HOMs) of superconducting accelerators especially for energy-recovery linacs of high current operation. Though various types of HOM couplers, beam line HOM dampers and waveguide HOM couplers have been developed, there are some problems such as inner conductor heating of output connector for HOM couplers and low packing factor for beam line HOM dampers. We propose new design of HOM coupler. This coupler consists of a coaxial line coupled with a cavity or a beam pipe and a rounded waveguide which cuts off the accelerating mode. The rounded waveguide is similar to a coaxial line and the inner conductor and outer conductor are connected with a plate which corresponds to waveguide side wall. This enables the inner connector cooled down efficiently through the outer conductor. The calculation results of MW-STUDIO will be presented.  
 
THP070 Analysis of High Order Modes in 1.3 GHz CW SRF Electron Linac for a Light Source cavity, linac, dipole, emittance 1085
 
  • A.I. Sukhanov, A. Vostrikov, V.P. Yakovlev
    Fermilab, Batavia, USA
  
  Design of a Light Source (LS) based on the continuous wave superconducting RF (CW SRF) electron linac is currently underway. This facility will provide soft coherent X-ray radiation for a broad spectrum of basic research applications. Quality of the X-ray laser radiation is affected by the electron beam parameters such as the stability of the transverse beam position and longitudinal and transverse beam emittances. High order modes (HOMs) excited in the SRF structures by a passing beam may deteriorate the beam quality and affect the beam stability. Deposition of HOM energy in the walls of SRF cavities adds to the heat load of the cryogenic system and leads to the increased cost of building and operation of the linac. In this paper we evaluate effects of HOMs in an LS CW SRF linac based on Tesla-type 9-cell 1.3 GHz cavities. We analyze non-coherent losses and resonance excitation of HOMs. We estimate heat load due to the very high frequency HOMs. We study influence of the HOMs on the transverse beam dynamics.  
 
THP071 HOM Studies of the Cornell ERL Main Linac Cavity in the Horizontal Test Cryomodule cavity, linac, cryomodule, experiment 1090
 
  • N.R.A. Valles, R.G. Eichhorn, D.A. Goldman, G.H. Hoffstaetter, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: Supported by NSF grant DMR-0807731
The Cornell energy recovery linac will accelerate a 100 mA beam to 5 GeV, while maintaining very low emittance (30 pm at 77 pC bunch charge). A major challenge to running such a large current continuously through the machine is the effect of strong higher-order modes (HOMs) in the SRF cavities that can lead to beam breakup. This paper presents the results of HOM studies for the prototype 7-cell cavity installed in a horizontal test cryomodule (HTC). HOM measurements were done for three HTC assembly stages, from initial measurements on the bare cavity to being fully outfitted with side-mounted RF input coupler and beam line HOM absorbers. We compare the simulated results of the optimized cavity geometry with measurements from all three HTC experiments, demonstrating excellent damping of all dipole higher order modes. 		 
 
THP073 HOM Dampers and Waveguide for the Short Pulse X-Ray (SPX) Project cavity, cryomodule, vacuum, damping 1098
 
  • G.J. Waldschmidt, B. Brajuskovic, D.J. Bromberek, J.D. Fuerst, J.P. Holzbauer, A. Nassiri, Y. Shiroyanagi, G. Wu
    ANL, Argonne, USA
  • V.D. Shemelin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The production of HOM dampers for the superconducting SPX cavities has been undertaken at the Advanced Photon Source. The dampers are vacuum compatible loads that utilize a four wedge design in WR284 rectangular waveguide. The rf lossy material consists of hexoloy silicon carbide (SiC) due to its suitable mechanical and electrical material properties. Issues regarding manufacturing consist of initial SiC material failure due to fabrication stresses as well as substandard soldering bonds of the SiC to the copper damper bodies. In addition, integration into the cryomodule consists of rf, thermal, and mechanical design considerations of the dampers and the waveguide transmission lines. An analysis of the manufacturing and integration issues and remedies are discussed further in this paper. 		 
 
THP094 Beam Induced HOM Analysis in STF cavity, dipole, alignment, cryomodule 1144
 
  • A. Kuramoto
    Sokendai, Ibaraki, Japan
  • H. Hayano
    KEK, Ibaraki, Japan
  
  Requirements of superconducting cavity (SC) alignment for ILC are less than 300 μm offset and 300 μrad tilt with respect to cryomodule. It is necessary to measure their offset and tilt inside of cryomodule. Cavity offset has been already measured by using beam induced HOM at FLASH in DESY. Cavity deformation during assembly and by cooling contraction has not been examined yet. To detect their tilt and bending, we measured HOM signals with beam trajectory sweep. Our interesting modes are pi over nine mode in the first dipole passband (TE111-1) which is trapped mode has maximum radial electric field in the middle cell and beam pipe modes localized in the both end-group of the SC. These modes tell us electrical center of middle cell and electrical centers at both beam pipe. We can know cavity tilt and bending from combinations of them. The experiment to find these HOM was performed at STF accelerator. Electron beam extracted from the RF Gun was accelerated to 40 MeV by the SC cavities. We could find TE111-1 and beam pipe modes. These HOM signals were correlated with beam orbit, accelerating field gradient. The detailed data analysis is introduced in this paper.  
 
THP097 Use of Waveguide Probes as Beam position and Tilt Monitoring Diagnostics with Baseline and Alternative Superconducting Deflecting Cavities for the APS Upgrade cavity, monitoring, diagnostics, dipole 1155
 
  • X. Sun, G. Decker, G. Wu
    ANL, Argonne, USA
  
  Funding: *Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC-02-06CH11357.
A set of superconducting deflecting cavities were studied for the APS Upgrade. A TM-mode baseline deflecting cavity design has been developed and prototyped, while an alternative design based on a TE-like mode is being studied. Waveguide field probes associated with the baseline and alternative superconducting deflecting cavities are explored as beam position and tilt monitoring diagnostics. Microwave Studio was used to simulate the technique of detecting the fields excited by a Gaussian bunch passing through the cavities to determine beam position relative to the electrical center. Probes installed on the horizontal midplane in the beam pipe are promising diagnostics for monitoring beam position and tilt in both designs. The probes in the power coupler also work as beam position monitors for the alternative deflecting cavities. 		 
 
FRIOA02 Developing Quarter Wave SRF Cavities for Hadron Colliders cavity, electron, collider, SRF 1165
 
  • Q. Wu
    BNL, Upton, Long Island, New York, USA
  
  Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with LARP and the U.S. DOE
Quarter Wave Resonators (QWRs) have been widely used in low-beta accelerators around the world because of their compact size at low frequency. Recently, application of QWRs is carrying over into hadron colliders aiming at various goals. A 56 MHz superconducting QWR is under testing at Brookhaven National Lab (BNL). It will be installed in the Relativistic Hadron Ion Collider (RHIC) as a storage cavity, which would be the first QWR operating in a high energy storage ring. A Compact crab cavity using QWR concept is another active SRF project at BNL. This crab cavity is a candidate for the Large Hadron Collider HiLumi upgrade, as well as for the future electron-ion collider (eRHIC). We report the design, fabrication, and testing results for the QWRs for hadron colliders under development at BNL. 		 
slides icon Slides FRIOA02 [10.542 MB]  
 
FRIOA04 Superconducting RF-Dipole Deflecting and Crabbing Cavities cavity, dipole, impedance, luminosity 1176
 
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  
  Recent interests in designing compact deflecting and crabbing structures for future accelerators and colliders have initiated the development of novel rf structures. The superconducting rf-dipole cavity is one of the first compact designs with attractive properties such as higher gradients, higher shunt impedance, the absence of lower order modes and widely separated higher order modes. Two rf-dipole designs of 400 MHz and 499 MHz have been designed, fabricated and tested as proof-of-principle designs of compact deflecting and crabbing cavities for the LHC high luminosity upgrade and Jefferson Lab 12 GeV upgrade. The first rf tests have been performed on the rf-dipole geometries at 4.2 K and 2.0 K in a vertical test assembly with excellent results. The cavities have achieved high gradients with high intrinsic quality factors, and multipacting levels were easily processed.  
slides icon Slides FRIOA04 [6.218 MB]  
 
FRIOB03 Development of 650 MHz Cavities for the GeV Proton Accelerator in Project X cavity, SRF, electron, proton 1193
 
  • S.S. Som, P. Bhattacharyya, A. Dutta Gupta, S. Ghosh, A. Mandal, S. Seth
    VECC, Kolkata, India
  
  Funding: DAE, Government of India
Project X is a GeV range high intensity proton linear accelerator being developed at Fermilab, USA in collaboration with various American and Indian laboratories as well. In stage-1 of the project, the CW linac structures with different velocity factor (beta) accelerate proton up to 3 GeV at an average beam current of 1 mA. For acceleration from 180 to 480 MeV,the development of 650 MHz, beta 0.61, 5-cell elliptical SRF cavities has been taken up by VECC. The EM design and analysis of this cavity, carried out using 2D and 3D codes, will be discussed along with its structural and mechanical modal analysis. This design has been compared with the designs made by JLab and Fermilab. The presence of higher order modes (HOMs)for the said cavity has been thoroughly examined. The multipacting analysis will be presented using 2D code and also 3D CST Particle Studio code with due consideration of Furman model for secondary electron emission comprising of true, elastic and rediffused secondary electrons. The prototype development and low power testing of this cavity will be discussed here. The talk will be concluded with the probable SRF challenges to be faced in the development of the cavity. 		 
slides icon Slides FRIOB03 [39.119 MB]  
 
FRIOC02 ESS Elliptical Cavities and Cryomodules cavity, cryomodule, proton, cryogenics 1218
 
  • G. Devanz, P. Bosland, M. Desmons, P. Hardy, F. Leseigneur, M. Luong, F. Peauger, J. Plouin, D. Roudier
    CEA/DSM/IRFU, France
  • N. Bazin
    CEA/IRFU, Gif-sur-Yvette, France
  • G. Costanza
    Lund University, Lund, Sweden
  • G. Olivier
    IPN, Orsay, France
  
  The accelerator of the European Spallation Source (ESS) is a 5 MW proton linac to be built in Lund Sweden. Its superconducting section is composed of 3 cavity families: double spoke resonators, medium beta and high beta elliptical multicell cavities. This paper presents the electromagnetic and mechanical design of the 704.42 MHz elliptical cavities. Both elliptical famillies are housed in 4-cavity cryomodules which share a common design and set of components which will be described here.  
slides icon Slides FRIOC02 [3.475 MB]