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cryomodule

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MO103 SNS Superconducting Linac Operational Experience and Upgrade Path cavity, linac, SRF, HOM 11
 
  • S.-H. Kim
    ORNL, Oak Ridge, Tennessee
 
 

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
The SNS Superconducting Linac (SCL) has been providing the main acceleration in two different accelerating sections with 33 medium beta and 48 high beta superconducting radio-frequency (SRF) 6-cell cavities. The use of superconducting elliptical cavities for particles whose velocity are less than the speed of light, make this accelerator a very important milestone for learning operating conditions of this cavity type. Since the SNS SCL is the first large-scale high energy pulsed-superconducting proton linac that provides high beam power utilizing H- beams, many aspects of its performance were unknown and unpredictable. A large amount of data has been collected on the pulsed behavior of cavities and cryomodules at various repetition rates and at various temperatures. This experience will be of great value in determining future optimizations of SNS as well in guiding in the design and operation of future pulsed superconducting linacs. This paper describes the details of the rf properties, performances, path-forward for the SNS power ramp-up goal, and upgrade path of the SNS superconducting linac.

 

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MOP018 ISAC-II Superconducting Linac Upgrade - Design and Status cavity, ISAC, linac, vacuum 97
 
  • R.E. Laxdal, R.J. Dawson, M. Marchetto, A.K. Mitra, W.R. Rawnsley, T.C. Ries, I. Sekachev, V. Zvyagintsev
    TRIUMF, Vancouver
 
 

The ISAC-II superconducting linac, operational since April 2006, adds 20 MV accelerating potential to the ISAC Radioactive Ion Beam (RIB) facility. An upgrade to the linac, in progress, calls for the addition of a further 20 MV of accelerating structure by the end of 2009. The new installation consists of twenty 141 MHz quarter wave cavities at a design beta of 11%. The cavities will be housed in three cryomodules with six cavities in the first two cryomodules and eight cavities in the last. A second Linde TC50 refrigerator has been installed and commissioned to provide cooling for the new installation. The design incorporates several new features as improvements to the existing cryomodules. They include a four point support frame for the cavity strongback, a modified LN2 circuit internal to the cryomodule and a new design for the mechanical motion of the rf coupling loop. A summary of the design and the current status of the cryomodule production and supporting infrastructure will be presented.

 
MOP028 A SC Upgrade for the REX-ISOLDE Accelerator at CERN cavity, linac, ion, acceleration 124
 
  • M. Pasini, S. Calatroni, N. Delruelle, M. Lindroos, V. Parma, T. Trilhe, D. Voulot, F.J.C. Wenander
    CERN, Geneva
  • R.M. Jones
    UMAN, Manchester
  • P.A. McIntosh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
 

The High Intensity and Energy ISOLDE (HIE-ISOLDE) proposal is a major upgrade of the existing ISOLDE and REX-ISOLDE facilities with the objective of increasing the energy and the intensity of the delivered radioactive ion beam. For the energy increase a staged construction of a superconducting linac based on sputtered quarter wave cavities is foreseen downstream of the present normal conducting linac. A funded R&D program has been launched at the end of 2007 in order to prepare a full Technical Design Report covering all the issues of such a linac, including cavity prototyping and testing, cryomodule design, beam dynamics and beam diagnostics. We report here on the status and planning of the R&D activities for the SCREX-ISOLDE linac.

 

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MOP029 Beam Dynamics Studies for the SCREX-ISOLDE Linac at CERN linac, emittance, cavity, simulation 127
 
  • M. Pasini, D. Voulot
    CERN, Geneva
  • M.A. Fraser, R.M. Jones
    UMAN, Manchester
 
 

For the REX-ISOLDE upgrade a superconducting linac based on 101.28 MHz Quarter Wave Resonators (QWRs) is foreseen downstream the normal conducting (NC) linac. Currently the REX-ISOLDE linac can accelerate ions with a mass to charge ratio in the range of 3 < A/q < 4.5 and up to an energy of 3 MeV/u. The upgrade aims to reach a final beam minimum energy of 10 MeV/u for A/q=4.5 in two main stages. The first stage consists of installing two cryomodules loaded with 10 cavities able to reach 5.5 MeV/u at the end of the present linac and the second consists of replacing part of the existing NC linac and adding further cryomodules. We report here on a beam dynamics study of the accelerator for the two installation stages and the transport line to the experimental station.

 
MOP053 The SPIRAL 2 Superconducting Linac cavity, linac, vacuum, coupling 196
 
  • R. Ferdinand
    GANIL, Caen
  • P.-E. Bernaudin, P. Bosland
    CEA, Gif-sur-Yvette
  • Y. Gómez-Martínez
    LPSC, Grenoble
  • T. Junquera, G. Olry, H. Saugnac
    IPN, Orsay
 
 

The SPIRAL2 superconducting linac is composed of 2 cryomodule families, basically one of low beta, called Cryomodule A, and one of high beta, called Cryomodule B. The low beta family is composed of 12 single cavity cryomodule. The high energy section is composed of 7 cryomodules hosting 2 cavities each. According to beam dynamics calculations all the cavities will operate at 88 MHz: one family at beta=0.07, and one at beta=0.12. The design goal for the accelerating field Eacc of the SPIRAL2 QWRs is : 6.5 MV/m. The configuration, cavities and cryomodule tests and status and the foreseen linac tuning will be described.

 
MOP111 Control Systems for Linac Test Facilities at Fermilab controls, EPICS, linac, low-level-rf 334
 
  • J.F. Patrick, S.L. Lackey
    Fermilab, Batavia
 
 

Funding: *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Fermilab* is constructing superconducting rf test facilities for development of technologies to be used in future Linac projects. Two of these facilities, the High Intensity Neutrino Source and the New Muon Laboratory, are proto-type Linacs which will run with beam. The requirements for these facilities vary but all involve collaboration and flexibility for integrating various new instruments. Tight timing requirements and automation are also required. Some facilities require integration into the existing Fermilab Control system. The controls also must be robust so as not to interfere with the main purpose of the facilities. We will outline the plan for accomplishing this task as well as the current status.

 
TU102 Status of the Construction of the SPIRAL2 Accelerator at GANIL linac, ion, cavity, rfq 348
 
  • T. Junquera
    IPN, Orsay
 
 

The superconducting linac for the SPIRAL2 radioactive ion beam facility at GANIL is in the construction phase. The prototype components have been constructed and are being tested. A status report on the activities and future plans will be given.

 

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TU201 Linac R&D for the ILC Technical Design Report linac, linear-collider, collider, cavity 359
 
  • M.C. Ross
    Fermilab, Batavia
 
 

The International Linear Collider (ILC) Technical Design Report (TDR) is scheduled for publication in 2012. The TDR will include an updated ILC baseline technical design description, results from critical R&D programs in support of key parameter choices, and one or more models for a Project Implementation Plan with an associated value estimate. The focus of linac R&D is to:

  1. achieve the specified superconducting rf cavity accelerating gradient of 35 MV/m with a corresponding production yield,
  2. design and test cryomodule assemblies that include "plug-compatible" sub-components with specified interfaces, and
  3. demonstrate system performance with nominal ILC high intensity beams.
In keeping with the international nature of the project, R&D is underway at ILC partner institutions with results and infrastructure that are shared throughout the project effort. This paper describes the technical challenges to be addressed and summarizes ongoing activities and plans.

 

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TU202 ILC Siting in Moscow Region Near Dubna and ILC Related Activity at JINR site, laser, diagnostics, linac 360
 
  • G. Shirkov, Ju. Boudagov, Yu.N. Denisov, I.N. Meshkov, A.N. Sissakian, G.V. Trubnikov
    JINR, Dubna, Moscow Region
 
 

The report presents the development of investigations on ILC siting in the Dubna region and ILC related activity at JINR. The report will describe the fields of activities ongoing to support the ILC at JINR. In addition, other linear accelerator activities at JINR will be summarized.

 

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TUP041 Superconducting Options for the UK's New Light Source Project FEL, linac, SRF, cavity 486
 
  • P.A. McIntosh, R. Bate, C.D. Beard, D.M. Dykes, S.M. Pattalwar
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
 

The UK's new light source project was officially launched on April 11th 2007, which will be based on advanced conventional and free electron lasers, with unique and world leading capabilities. User consulation exercises have already been initiated to determine the fundamental photon output requirements for such a machine. In order to match a nominal requirement for high repetition rates (extending up to 1 MHz), a series of superconducting rf (SRF) linac options have been investigated, reflecting varied beam loading conditions and subsequent high and low power rf solutions.

 
TH102 SRF Developments for Ion Acceleration cavity, linac, ion, niobium 730
 
  • G. Olry
    IPN, Orsay
 
 

The talk will provide an overview of the SRF development toward the acceleration of light and heavy ions including QWRs, HWRs, spoke and CH cavities.

 

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TH103 Developing Facilities for SNS Cryomodule Performance Improvements cavity, linac, radiation, shielding 735
 
  • J. Mammosser
    ORNL, Oak Ridge, Tennessee
 
 

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
Superconducting rf cavity facilities are currently being developed at SNS aimed at addressing the limitations and availability of installed cavities and the direct support of the future power upgrade plans. Efforts are directed towards development of in situ repairs and processing techniques to increase available linac gradients. Procedures have been developed and implemented and the results will be presented for the repair of four cryomodules in the last year. Cryomodule testing facilities are being developed to further understand the collective limitations of installed cavities and spare cryomodule production is underway to develop and fabricate two high beta and one medium beta cryomodules. The direction and status of SRF facilities will be presented.

 

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THP005 Tests of Wire Sublimations Very Close to SPIRAL 2 Superconducting Cavity cavity, diagnostics, linac, vacuum 783
 
  • R. Ferdinand, E. Gueroult, P. Robillard, J.L. Vignet
    GANIL, Caen
  • P. Ausset, D. Longuevergne, G. Olry, H. Saugnac, P. Szott
    IPN, Orsay
 
 

The construction of the new Spiral 2 facility has started in Caen (France) at the National Heavy Ions Accelerator Center (GANIL). The SPIRAL 2 project is based on a multi-beam Superconducting Linac Driver delivering 5 mA deuterons up to 40 MeV and 1 mA heavy ions up to 14.5 MeV/u delivering different Radioactive Isotope Beams (RIB). The LINAC is composed of 2 cryomodule families. The low energy family (cryomodules A) is composed of 12 cryomodules housing a single cavity at beta=0.07. The "high" energy family (cryomodules B) is composed of 7 cryomodules housing 2 cavities at beta=0.12. In between cryomodules are located the focalisation quadrupoles and the diagnostic boxes. Strong beliefs forbid the use of interceptives diagnostics around superconducting cavities. We simulated the use of wires for diagnostics in the linac, sublimating 14 wires of tungsten, Niobium and carbon while operating the B cavity at full performances. The first results describe in this paper looks promising.

 
THP008 A Novel Frequency Tuning System Based on Movable Plunger for SPIRAL2 High-Beta Superconducting Quarter-Wave Resonator cavity, niobium, simulation, insertion 789
 
  • D. Longuevergne, S. Blivet, G. Martinet, G. Olry, H. Saugnac
    IPN, Orsay
 
 

SPIRAL2 aims at building a multi-purpose facility dedicated to nuclear physics studies, including the production of rich-neutrons isotopes. The multi-beam linear accelerator is composed of superconducting accelerating modules and warm focusing magnets. IPN Orsay is in charge of the high energy accelerating modules, each hosting two superconducting (β = 0.12) quarter-wave resonators operating at an accelerating field of 6.5 MV/m at 88 MHz. The static and dynamic frequency tuning is achieved by the insertion and motion of a niobium plunger into the magnetic field area. The efficiency of the tuning (1 kHz/mm) has been validated during the tests of the cryomodule. In this paper we discuss the impact of such a tuning system, based on experimental results on Spiral2 cavities, on the different aspects: maximum accelerating field, Qo slopes, quench, multipacting and microphonics.

 
THP009 RF and Cryogenic Tests of the First Beta 0.12 SPIRAL2 Cryomodule cavity, vacuum, cryogenics, linac 792
 
  • H. Saugnac, C. Commeaux, C. Joly, J. Lesrel, D. Longuevergne, F. Lutton, G. Martinet, G. Olry
    IPN, Orsay
  • R. Beunard, R. Ferdinand, M. Souli
    GANIL, Caen
  • Y. Gómez-Martínez, F. Vezzu
    LPSC, Grenoble
 
 

The SPIRAL2 project, installed in GANIL for Radioactive Ion Beam physics purposes requires the manufacturing of a multi beam driver. This driver is based on a superconducting Linac featuring two 88 MHz Quarter Wave Resonator families. IPN Orsay is in charge of the study and the assembly of the 7 high energy (beta = 0.12) cryomodules. Each cryomodule is composed of two QWRs, specified to operate at 4.2 K with a nominal accelerating gradient of 6.5 MV/m. A first qualifying cryomodule has been manufactured and tested at the beginning of 2008 in order to validate the resonator and the cryostat design before launching the serial production of the 6 remaining cryomodules. The paper presents the main results of this test and the cryomodule design in its final version.

 
THP019 Third Harmonic Superconducting Cavity Prototypes for the XFEL cavity, linac, HOM, pick-up 821
 
  • P. Pierini, A. Bosotti, N. Panzeri, D. Sertore
    INFN/LASA, Segrate (MI)
  • H.T. Edwards, M.H. Foley, E.R. Harms, D.V. Mitchell
    Fermilab, Batavia
  • J. Iversen, W. Singer, E. Vogel
    DESY, Hamburg
 
 

The third harmonic cavities that will be used at the injector stage in the XFEL to linearize the rf curvature distortions and minimize beam tails in the bunch compressor are based on the rf structures developed at FNAL for the DESY FLASH linac. The design and fabrication procedures have been modified in order to match the slightly different interfaces of XFEL linac modules and the procedures followed by the industrial production of the main (1.3 GHz) XFEL cavities. A revision of the helium vessel design has been required to match the layout of the cryomodule strings, and a lighter version of the tuner has been designed (derived from the 1.3 GHz ILC blade tuner activities). The main changes introduced in the design of the XFEL cavities and the preliminary experience of the fabrication of three industrially produced and processed third harmonic rf structures are described here.

 
THP025 Superconducting Quarter-Wave Resonators for the ATLAS Energy Upgrade cavity, linac, niobium, coupling 836
 
  • M.P. Kelly, J.D. Fuerst, S.M. Gerbick, M. Kedzie, P.N. Ostroumov, K.W. Shepard, G.P. Zinkann
    ANL, Argonne
 
 

A set of six new 109 MHz β=0.15 superconducting quarter-wave resonators (QWR) has been built at ANL as part of an upgrade to the ATLAS superconducting heavy-ion linac. The final cavity string assembly will also use many of the techniques needed for the next generation of large high-performance ion linacs such as the U.S. Department of Energy's FRIB project. Single-cavity cold tests at T=4.5 K have been performed for three cavities with moveable coupler, rf pickup, and VCX fast tuner as required for the full 6-meter cryomodule assembly. The average maximum accelerating gradient of 4 cavities (3 new + 1 prototype), is EACC=11.2 MV/m (BPEAK=65 mT). Clean cavity string assembly techniques, required here and for most future SRF ion linacs, are fairly well developed. Details on cavity performance including high-field cw operation, microphonics and fast tuning are presented.

 
THP027 Welding Helium Vessels to the 3.9 GHz Superconducting Third Harmonic Cavities cavity, electron, monitoring, emittance 842
 
  • M.H. Foley, T.T. Arkan, H. Carter, H.T. Edwards, J. Grimm, E.R. Harms, T.N. Khabiboulline, D.V. Mitchell, D.R. Olis, T.J. Peterson, P.A. Pfund, N. Solyak, D.J. Watkins, M. Wong
    Fermilab, Batavia
  • G. Galasso
    University of Udine, Udine
 
 

Funding: This work was supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The 3.9 GHz 3rd harmonic cavities are designed to serve as compensation devices for improving the longitudinal emittance of the free-electron laser FLASH at DESY. These cavities operate in the TM010 mode, and will be located between the injector and the accelerating cavities. Fermilab is obligated to provide DESY with a cryomodule containing four 3rd harmonic cavities. In this paper we discuss the process of welding helium vessels to these cavities. Included will be a description of the joint designs and weld preparations, development of the weld parameters, and the procedure for monitoring the frequency spectrum during TIG welding to prevent the cavity from undergoing plastic deformation. Also discussed will be issues related to qualifying the dressed cavities as exceptional vessels (relative to the ASME Boiler and Pressure Vessel Code) for horizontal testing and eventual installation at DESY, due to the necessary use of non-ASME code materials and non-full penetration electron beam welds.

 
THP028 Status of 3.9 GHz Superconducting RF Cavity Technology at Fermilab cavity, HOM, alignment, status 845
 
  • E.R. Harms, T.T. Arkan, V.T. Bocean, H. Carter, H.T. Edwards, M.H. Foley, T.N. Khabiboulline, M.W. McGee, D.V. Mitchell, D.R. Olis, A.M. Rowe, N. Solyak
    Fermilab, Batavia
 
 

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Fermilab is involved in an effort to design, build, test and deliver four 3.9 GHz superconducting rf cavities within a single cryomodule to be delivered to DESY as a 'third harmonic' structure for the FLASH facility to improve the longitudinal emittance. In addition to an overall status update we will present recent results from single 'dressed' cavity horizontal tests and shipping and alignment measurements.

 

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THP033 Superconducting Quarter-Wave Resonator Cavity and Cryomodule Development for a Heavy Ion Re-accelerator cavity, solenoid, ion, superconductivity 854
 
  • W. Hartung, J. Bierwagen, S. Bricker, C. Compton, J. DeLauter, P. Glennon, M. Hodek, M.J. Johnson, F. Marti, P.S. Miller, D. Norton, J. Popielarski, L. Popielarski, D. Sanderson, J. Wlodarczak, R.C. York
    NSCL, East Lansing, Michigan
  • A. Facco
    INFN/LNL, Legnaro, Padova
  • E.N. Zaplatin
    FZJ, Jülich
 
 

A superconducting linac is being planned for re-acceleration of exotic ions produced by the Coupled Cyclotron Facility at Michigan State University. The re-accelerator will include a gas stopper, a charge breeder, a normal conducting radio-frequency quadrupole, and two types of superconducting quarter-wave resonators (QWRs) for re-acceleration to energies of up to 3 MeV per nucleon initially, with a subsequent upgrade path to 12 MeV per nucleon. The QWRs (80.5 MHz, optimum beta = 0.041 and 0.085, made from bulk niobium) are similar to existing cavities presently used at INFN-Legnaro. The re-accelerator's cryomodules will accommodate up to 8 cavities, along with superconducting solenoids for focussing. Active and passive shielding is required to ensure that the solenoids' field does not degrade the cavity performance. First prototypes of both QWR types have been fabricated and tested. A prototype solenoid has been procured and tested. A test cryomodule has been fabricated: one QWR, one solenoid, and two other beam line elements have been installed inside. This paper will cover the re-accelerator cavity and cryomodule prototyping efforts, results so far, and future plans.

 

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THP039 SRF Cavity Imperfection Studies Using Advanced Shape Uncertainty Quantification Tools cavity, SRF, dipole, HOM 870
 
  • V. Akcelik, K. Ko, L. Lee, Z. Li, C.-K. Ng, L. Xiao
    SLAC, Menlo Park, California
 
 

Funding: Work supported by DOE contract DE-AC02-76SF00515.
The shape deviation of a SRF cavity from the design shape may result in significant impact on cavity performance and wakefields that could lead to unexpected effects in beam dynamics. Yet, most of these deviations are unknown in the final cavity installation because of the complicated process of assembly and tuning. It is desirable to be able to uncover such distortions using measurable rf quantities. With these data, the cavity performance can be analyzed and realistic tolerance criteria may be implemented in the cavity design and manufacture for quality assurance. To perform such analyses, SLAC has developed advanced Shape Determination Tools, under the SciDAC support for high performance computing, that recover the real cavity shape by solving an inverse problem. These tools have been successfully applied to analyze shape distortions to many SRF cavities, and identified the cause of unexpected cavity behaviors. The capabilities and applications of these tools will be presented.

 
THP054 Status of RF Sources in Super-Conducting RF Test Facility (STF) at KEK cavity, controls, LLRF, klystron 909
 
  • S. Fukuda, M. Akemoto, H. Hayano, H. Honma, H. Katagiri, S. Kazakov, S. Matsumoto, T. Matsumoto, S. Michizono, H. Nakajima, K. Nakao, T. Shidara, T. Takenaka, Y. Yano, M. Yoshida
    KEK, Ibaraki
 
 

Phase 0.5 and Phase 1.0 of the Superconducting RF Test Facility (STF) have been developed since 2005 in KEK. We have completed the two rf-sources and they have been used for the evaluation for the components of power distribution system (PDS) and couplers which were installed in the 5m-cryomodules. We have developed some rf components which is used in the power distribution system(PDS). Phase 1.0 have been conducted now and we attempt the R&D of PDS required in ILC project. This report describes the recent status of the rf source of STF in KEK including the modulator, PDS and LLRF.

 
THP073 Progress in L-Band Power Distribution System R&D at SLAC cavity, coupling, acceleration, linac 960
 
  • C.D. Nantista, C. Adolphsen, F. Wang
    SLAC, Menlo Park, California
 
 

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.
We report on the L-band rf power distribution system (PDS) developed at SLAC for Fermilab's NML superconducting test accelerator facility. The makeup of the system, which allows tailoring of the power distribution to cavities by pairs, is briefly described. Cold test measurements of the system and the results of high power processing are presented. We also investigate the feasibility of eliminating the expensive, lossy circulators from the PDS in the ILC linacs by taking advantage of our scheme of pair-feeding through 3-dB hybrids. A computational model is used to simulate the impact on field stability of inter-cavity coupling due to reduced isolation. Measurements of typically achievable hybrid port isolations provide the likely magnitude for such coupling.

 
THP076 Last SPIRAL 2 10 kW CW RF Coupler Design cavity, simulation, linac, resonance 969
 
  • Y. Gómez-Martínez, T. Cabanel, J. Giraud, D. Marchand, R. Micoud, F. Vezzu
    LPSC, Grenoble
 
 

The first tests of the SPIRAL 2 coupler have been done successfully in the B-cryomodule of the SPIRAL2 linac. It led to an updated design. We present the new design as well as the results of the last test and conditioning.

 

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THP093 Power Coupler and Tuner Development for Superconducting Quarter-Wave Resonators vacuum, cavity, niobium, superconductivity 1005
 
  • J. Wlodarczak, P. Glennon, W. Hartung, M. Hodek, M.J. Johnson, D. Norton, J. Popielarski
    NSCL, East Lansing, Michigan
 
 

The construction of a reaccelerator for secondary ion beams is currently underway at the National Superconducting Cyclotron Laboratory (NSCL). The reaccelerator linac will use superconducting quarter-wave resonators (QWR) operating at 80.5 MHz with beta = 0.041 and beta = 0.085. A coaxial probe-type rf fundamental power coupler (FPC) will be used for both QWR types. The power coupler makes use of a commercially-available feedthrough to minimize the cost. The FPC has been simulated and optimized for operation at 80.5 MHz using a finite element electromagnetics code. Prototype FPC have been fabricated and conditioned with traveling wave and standing wave power using a 1 kW amplifier. A niobium tuning plate is incorporated into the bottom flange of the QWR. The tuner is actuated by a stepping motor for slow (coarse) tuning and a stacked piezoelectric element in series for fast (fine) tuning. A prototype tuner for the beta = 0.041 QWR has been tested on the cavity at room temperature. This paper will cover the design, fabrication, and testing of the prototype coupler and tuner.

 
THP120 Concept Design Studies of the REX-ISOLDE Cryomodules at CERN vacuum, cavity, linac, solenoid 1081
 
  • V. Parma, S. Calatroni, N. Delruelle, J. Hansen, C. Maglioni, M. Modena, M. Pasini, T. Trilhe
    CERN, Geneva
  • S.M. Pattalwar
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
 

The High Intensity and Energy (HIE) proposal plans a major upgrade of the existing ISOLDE and REX-ISOLDE facilities at CERN, with the objective of substantially increasing the energy and the intensity of the delivered radioactive ion beams. In the frame of this upgrade activity, a superconducting linac, based on Nb sputtered Quarter Wave Resonators (QWRs) is proposed to be installed downstream of the present normal conducting machine. The present design of the accelerator lattice features housing of five high-beta cavities (β=10.6%) and a superconducting solenoid in a common cryomodule. In most of the existing low-energy heavy-ion installations worldwide, insulation and beam vacuum are in common, with the risk of cavity surface contamination in case of accidental leak to the cryostat vessel. Following a concept study, we report in this paper on three design options, namely cryomodules with common vacuum, with separate or with hybrid vacuum systems (the latter having a low conductance between insulation and beam vacuum) and compare them in terms of technical complexity, performance, reliability and maintainability.

 
THP122 Overview of the First Five Refurbished CEBAF Cryomodules cavity, vacuum, electron, linac 1084
 
  • M.A. Drury, E. Daly, G.K. Davis, J.F. Fischer, C. Grenoble, J. Hogan, F. Humphry, L.K. King, J.P. Preble, K. Worland
    JLAB, Newport News, Virginia
 
 

Funding: Authored by JSA, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
The Thomas Jefferson National Accelerator Facility is currently engaged in a cryomodule refurbishment project. The goal of this project is robust 6 GeV, 5 pass operation of the Continuous Electron Beam Accelerator Facility (CEBAF). The scope of the project includes removing, refurbishing and replacing ten CEBAF cryomodules at a rate of three per year. Refurbishment includes reprocessing of SRF cavities to eliminate field emission and increase the nominal gradient from the original 5 MV/m to 12.5 MV/m. New 'dogleg' couplers between the cavity and helium vessel flanges will intercept secondary electrons that produce arcing at the 2 K ceramic window in the Fundamental Power Coupler (FPC). Modification of the Qext of the FPC will allow higher gradient operations. Other changes include new ceramic rf windows for the air to vacuum interface of the FPC and improvements to the mechanical tuners. Any damaged or worn components will be replaced as well. Currently, five refurbished cryomodules have been installed in CEBAF. These cryomodules have been installed in CEBAF and are currently operational. This paper will summarize the test results and current operational experience.