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MO102 Status of the European XFEL Project linac, SRF, electron, undulator 6
 
  • H. Weise
    DESY, Hamburg
 
 

The internationally organized European XFEL free-electron laser is under construction at the Deutsches Elektronen-Synchrotron (DESY). The project is the first large scale application of the TESLA technology developed over the last 15 years. Superconducting accelerating cavities will be used to accelerate the electron beam to an energy of up to 17.5 GeV. Recently an energy reduction by 20% to 14 GeV was discussed as a reasonable compromise between cost aspects and scientific potential of the facility. With realistic assumptions on lower beam emittance, the design photon beam parameters will be achieved. The talk will briefly summarize the overall XFEL design before presenting details about the status of the superconducting linac. The activities within the international collaboration will be described. Final prototyping, industrialization and commissioning new infrastructure are the actual challenges. Contracts for long lead items are placed.

 

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MO103 SNS Operation at 1 MW and Beyond linac, target, neutron, ion 11
 
  • S. Henderson
    ORNL, Oak Ridge, Tennessee
 
 

This talk will present the stutus of SNS operation at 1MW and plan beyond it.

 
MO201 Status and Challenges of the Spiral2 Facility linac, cryomodule, ion, rfq 16
 
  • R. Ferdinand, P. Bertrand
    GANIL, Caen
 
 

SPIRAL 2 is a new European facility for Radioactive Ion Beams being constructed at the GANIL laboratory (Caen, France). It is based on a High Intensity CW multi-ion Accelerator Driver (Superconducting Linac), delivering beams to a High Power Production system (converter, target, and ion source), producing and post-accelerating Radioactive Ion Beams with intensities never reached before. The major components of the accelerator (injectors and SC Linac), have been presently ordered. The number of tested components is rapidly growing. The Superconducting Linac Accelerator incorporates many innovative developments of the Quarter-Wave resonators and their associated cryogenic and RF systems. The first beam is expected during autumn 2011. The first operation is scheduled for late 2012 with an initial experimental program prepared in the framework of a European Project, with many other international collaborating partners.

 
MO202 Operating Experience of the 20 MV Upgrade Linac cryomodule, linac, ISAC, TRIUMF 21
 
  • R.E. Laxdal, C.D. Beard, R.J. Dawson, K. Fong, A. Grassellino, M.P. Laverty, D. Longuevergne, M. Marchetto, A.K. Mitra, T.C. Ries, I. Sekachev, Q. Zheng, V. Zvyagintsev
    TRIUMF, Vancouver
 
 

The ISAC-II Phase II expansion includes the addition of 20 new quarter wave resonators in three cryomodules to double the energy gain of the ISAC-II superconducting linac. The rf cavities are produced in Canada. The talk will concentrate on the beam commissioning (scheduled for March 2010) and early operating experience.

 
MO203 ReA3 - the Rare Isotope Re-accelerator at MSU ion, linac, rfq, cryomodule 26
 
  • O.K. Kester, D. Bazin, C. Benatti, J. Bierwagen, G. Bollen, S. Bricker, S. Chouhan, C. Compton, A.C. Crawford, K.D. Davidson, J. DeLauter, M. Doleans, L.J. Dubbs, K. Elliott, W. Hartung, M.J. Johnson, S.W. Krause, A. Lapierre, F. Marti, J. Ottarson, G. Perdikakis, J. Popielarski, L. Popielarski, M. Portillo, R. Rencsok, D.P. Sanderson, S. Schwarz, N. Verhanovitz, J.J. Vincent, J. Wlodarczak, X. Wu, J. Yurkon, A. Zeller, Q. Zhao
    NSCL, East Lansing, Michigan
  • A. Schempp, J.S. Schmidt
    IAP, Frankfurt am Main
 
 

Rare isotope beam (RIB) accelerator facilities provide rich research opportunities in nuclear physics. The National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) is constructing a RIB facility, called ReA3. It will provide unique low-energy rare isotope beams by stopping fast RIBs and reaccelerating them in a compact linac. ReA3 comprises gas stopper systems, an Electron Beam Ion Trap (EBIT) charge state booster, a room temperature radio frequency quadrupole (RFQ), a linac using superconducting quarter wave resonators (QWRs) and an achromatic beam transport and distribution line to the new experimental area. Beams from ReA3 will range from 3 MeV/u for heavy ions to about 6 MeV/u for light ions, as the charge state of the ions can be adjusted by the EBIT. ReA3 will initially use beams from NSCL's Coupled Cyclotron Facility (CCF). Later ReA3 will provide reacceleration capability for the Facility for Rare Isotope Beams (FRIB), a new national user facility funded by the Department of Energy (DOE) that will be hosted at MSU. The ReA3 concept and status of ReA3 will be presented, with emphasis on the comissioning of the facility, which is underway.

 

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MO302 S1-Global Collaborative Efforts - 8-Cavity-Cryomodule: 2 FNAL, 2 DESY and 4 KEK cryomodule, vacuum, linac, linear-collider 31
 
  • N. Ohuchi, M. Akemoto, S. Fukuda, H. Hayano, N. Higashi, E. Kako, H. Katagiri, Y. Kojima, Y. Kondou, T. Matsumoto, H. Matsushita, S. Michizono, T. Miura, H. Nakai, H. Nakajima, S. Noguchi, M. Satoh, T. Shidara, T. Shishido, T. Takenaka, A. Terashima, N. Toge, K. Tsuchiya, K. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, K. Yokoya, M. Yoshida
    KEK, Ibaraki
  • C. Adolphsen, C.D. Nantista
    SLAC, Menlo Park, California
  • T.T. Arkan, S. Barbanotti, H. Carter, M.S. Champion, R.D. Kephart, J.S. Kerby, D.V. Mitchell, Y. Orlov, T.J. Peterson, M.C. Ross
    Fermilab, Batavia
  • A. Bosotti, C. Pagani, R. Paparella, P. Pierini
    INFN/LASA, Segrate (MI)
  • D. Kostin, L. Lilje, A. Matheisen, W.-D. Möller, N.J. Walker, H. Weise
    DESY, Hamburg
 
 

In an attempt at demonstrating an average field gradient of 31.5 MV/m as per the design accelerating gradient for ILC, a program called S1-Global is in progress as an international research collaboration among KEK, INFN, FNAL, DESY and SLAC. The design of the S1-G cryomodule began at May 2008 by INFN and KEK. The S1-Global cryomodule was designed to contain eight superconducting cavities from FNAL, DESY and KEK, and to be constructed by joining two half-size cryomodules, each 6 m in length. The module containing four cavities from FNAL and DESY was constructed by INFN. Four KEK cavities have been assembled in the 6 m module which KEK fabricated. All major components were transported to KEK from INFN, FNAL and DESY in December 2009. The assembly of the two 6-m cryomodules started from January 2010 in a collaborative work of FNAL, DESY, INFN and KEK. The construction of the S1-G cryomodule will complete in May, and the cool-down of the S1-G cryomodule is scheduled from June 2010 at the KEK-STF. In this paper, the construction and the cold tests of the S1-Global cryomodule in the worldwide research collaboration will be presented.

 

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MO304 3.9 GHz Cavity Module for Linear Bunch Compression at FLASH HOM, electron, photon, simulation 41
 
  • H.T. Edwards, E.R. Harms
    Fermilab, Batavia
  • C. Behrens
    DESY, Hamburg
 
 

FNAL has contributed to FLASH at DESY the third harmonic accelerating system, which will provide better beams for the FEL facility. The FNAL accelerating module has been qualified above specs and will be operational in FLASH in Spring.

 

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MOP001 CTF3 Probe Beam LINAC Commissioning and Operations laser, linac, gun, emittance 46
 
  • W. Farabolini, D. Bogard, A. Curtoni, P. Girardot, F. Peauger, C.S. Simon
    CEA, Gif-sur-Yvette
  • E. Chevallay, M. Divall Csatari, N. Lebas, M. Petrarca
    CERN, Geneva
  • A. Palaia, R.J.M.Y. Ruber, V.G. Ziemann
    Uppsala University, Uppsala
 
 

The probe beam LINAC, CALIFES, of the CLIC Test Facility (CTF3) has been developed by CEA Saclay, LAL Orsay and CERN to deliver trains of short bunches (0.75 ps) spaced by 0.666 ps at an energy around 170 MeV with a charge of 0.6 nC to the TBTS (Two-beam Test Stand) intended to test the high gradient CLIC accelerating structures. Based on 3 former LIL accelerating structures and on a newly developed RF photo-injector, the whole accelerator is powered with a single 3 GHz klystron delivering pulses of 45 MW through a RF pulse compression cavity and a network of waveguides, splitters, phase-shifters and an attenuator. We relate here results collected during the various commissioning and operation periods which led to nominal performances and stable beam characteristics delivered to the TBTS. Progress has been made in the laser system for beam charge and stability, in space charge compensation for emittance, in RF compression law for energy and energy spread. The installation of a specially developed RF power phase shifter for the first accelerating structure used in velocity bunching allows the control of the bunch length.

 
MOP008 Reducing the Energy Spread of Recirculating Linac by Non-isochronous Beam Dynamics recirculation, electron, linac, quadrupole 64
 
  • R. Eichhorn, A. Araz, J. Conrad, F. Hug, M. Konrad, T. Quincey
    TU Darmstadt, Darmstadt
 
 

The Superconducting Linear Accelerator S-DALINAC at the University of Darmstadt (Germany) is a recirculating Linac with two recirculations. Currently acceleration in the Linac section is done on crest of the accelerating field. The recirculation path is operated achromatic and isochronous. In this recirculation scheme the energy spread of the resulting beam in the ideal case is determined by the electron bunch length. Taking into account the stability of the RF system the energy spread increases drastically. In this work we will present a new non-isochronous recirculation scheme which helps canceling out these errors from the rf-control. This scheme uses longitudinal dispersion in the recirculation pathes and an acceleration off-crest with a certain phase with respect to the maximum. We will present beam dynamic calculations which show the usability of this system even in a Linac with only two recirculations and first experimental results

 
MOP022 Tuning of CLIC Accelerating Structure Prototypes at CERN monitoring, coupling, target 97
 
  • A. Grudiev, A. Olyunin, J. Shi, W. Wuensch
    CERN, Geneva
 
 

An RF measurement system has been set up at CERN for use in the X-band accelerating structure development program of the CLIC study. Using the system, S-parameters are measured and the field distribution is obtained automatically by using a bead-pull technique. The corrections for tuning the structure are calculated from the result. Integrated software guides cell-by-cell tuning to obtain the correct phase advance and minimum reflection at the operation frequency. The detailed configuration of the system, as well as the semi-automatic tuning procedure, is presented along with a few examples of measurement and tuning of CLIC accelerating structure prototypes.

 
MOP027 Distributed RF Scheme (DRFS) - Newly Proposed HLRF Scheme for ILC klystron, power-supply, radiation, HLRF 112
 
  • S. Fukuda
    KEK, Ibaraki
 
 

Distributed RF Scheme (DRFS) was proposed for International Linear Collider (ILC) as a new HLRF scheme. After the ITRP recommendation, ILC technology was chosen to be superconducting technology and basic design was discussed and reported in the RDR on 2007. Aiming for the cost reduction, there have been proposed many ideas and summarized as SB2009 proposal. DRFS is the one of these proposals, and it is linked to the single tunnel plan. DRFS employs many small klystrons (750kW output power) which feed power to two superconducting cavities. 13 modulating anode klystrons are operated by a DC power supply and a modulating anode pulser. All required components are installed in a tunnel and therefore this scheme is a complete single tunnel layout. DRFS was proposed in 2008 and thereafter it has been discussed in web-ex meeting and GDE workshop. In this conference, concept and detailed design of DRFS are presented including the availability and operability. In order to show the feasibility of DRFS, KEK has a plan of demonstration employing the DRFS with two klystrons in the S1 global in the end of 2010. Presenter also discussed pros and cons comparing with the competing proposed scheme.

 
MOP029 S0-studies on ICHIRO 9-cell Cavities in Collaboration with KEK and Jlab HOM, superconductivity, electron, cathode 118
 
  • F. Furuta, K. Saito
    KEK, Ibaraki
  • G.V. Eremeev, R.L. Geng
    JLAB, Newport News, Virginia
  • T. Konomi
    Sokendai, Ibaraki
 
 

In 2008, KEK and Jlab did the collaboration of S0-study on ICHIRO 9-cell #5 which has no end groups on beam tubes. As S0 tight loop test, surface treatments and vertical tests were repeated on ICHIRO#5 at both of Jlab and KEK. Maximum gradients of 36.5MV/m at Jlab and 33.7MV/m at KEK were achieved so far. In this year, 2010, KEK and Jlab started new S0-study collaboration on ICHIRO 9cell #7 which has full end groups on beam tubes. ICHIR#7 was already sent to Jlab and VT as received was done. We will report the results of tight loop tests at Jlab.

 
MOP030 Status of Superconducting Cavity Development for ILC at MHI superconducting-cavity, status, HOM, niobium 121
 
  • H. Hitomi, H. Hara, K. Kanaoka, K. Sennyu, T. Yanagisawa
    MHI, Kobe
 
 

MHI's activities for ILC project will be shown.

 
MOP033 Low Energy RF Accelerator for Various Applications linac, gun, coupling, focusing 127
 
  • P.K. Ambattu, G. Burt, M.I. Tahir
    Cockcroft Institute, Lancaster University, Lancaster
  • P.A. Corlett, P.A. McIntosh, A.J. Moss
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
 

Compact X-ray sources are integral parts of systems used in medical, industrial and security applications. The X-ray dose rate for a particular application mainly depends on the energy and current of the beam used to hit the target, usually made of tungsten. In applications that need higher penetration (100s of mm in steel), the beam energy needed is in the range of 1-5 MeV which can only be obtained using an RF linear accelerator. In order to reduce the size of the linac, higher RF frequencies (X-band) should be used while in order to reduce the overall bulk, RF focusing is employed instead of solenoidal focusing. Thus the main attraction of an X-band linac compared to a lower frequency version is the amount of lead required for shielding the system, and hence its weight. For capturing and bunching the low energy dc beam, a bunching section is needed in front of the main linac. The bunching cavity can either be a part of the main linac cavity or an independently powered section which can be used for certain specific applications as a shorter 1 MeV linac. In this paper, the design and simulations of an X-band buncher to be suitable for compact X-ray sources is presented.

 
MOP036 Beam Commissioning of C-band Standing-wave Accelerator for X-ray Source linac, coupling, gun, electron 136
 
  • H.R. Yang, M.-H. Cho, S.D. Jang, S.H. Kim, W. Namkung, S.J. Park
    POSTECH, Pohang, Kyungbuk
  • K.H. Chung, K. Lee
    KAPRA, Cheorwon
  • J.-S. Oh
    NFRI, Daejon
 
 

A C-band standing-wave electron linac for a compact X-ray source is now being commissioned at ACEP (Advanced Center for Electron-beam Processing in Cheorwon, Korea). It is designed to produce 4-MeV electron beam with pulsed 50-mA, using a 5-GHz RF power generated by a magnetron with pulsed 1.5 MW and average 1.2 kW. The accelerating structure is a bi-periodic and on-axis-coupled one operated with π/2-mode standing-waves. It is consisted of 3 bunching cells, 6 accelerating cells and a coupling cell. As a result of measurements, the beam energy is almost 4 MeV. In this paper, we present the design details and the commissioning status.

 
MOP041 The Superconducting Cw-Linac-Demonstrator at Gsi linac, solenoid, ion, rf-amplifier 145
 
  • S. Mickat, W.A. Barth, L.A. Dahl, M. Kaiser
    GSI, Darmstadt
  • K. Aulenbacher
    IKP, Mainz
  • M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
    IAP, Frankfurt am Main
  • T. Weilbach
    HIM, Mainz
 
 

GSI applied for a new superconducting (sc) cw-LINAC in parallel to the existing UNILAC. Such a machine is highly desirable with respect to the progress in the field of Superheavy Elements (SHE) for example. The UNILAC at GSI is limited in providing a proper beam for SHE and in fulfilling the requirements for FAIR simultaneously. A sc CH-structure is the key component of the proposed efficient and compact linac. In first vertical rf-tests at the Institute of Applied Physics (IAP) maximum gradients up to 7 MV/m were achieved. The cavities for the cw-LINAC should be operated at 217 MHz providing gradients of about 5.1 MV/m at a total length of minimum 0.6 m . In a first step a prototype of such a sc cw-LINAC as a demonstrator is financed by the Helmholtz Institute Mainz (HIM). The demonstrator is the first section of the proposed cw-LINAC consisting of a sc CH-cavity embedded by two sc solenoids. The aim is a full performance test of the demonstrator with beam at the GSI high charge injector (HLI) in 2013. Presently the tendering of the solenoids, the cavity, the cryostat and the rf-amplifier is in preparation.

 
MOP045 Efficiency and Intensity Upgrade of the ATLAS Facility rfq, ion, cryomodule, electron 157
 
  • P.N. Ostroumov, R.V.F. Janssens, M.P. Kelly, S.A. Kondrashev, B. Mustapha, R.C. Pardo, G. Savard
    ANL, Argonne
 
 

ANL Physics Division is pursuing a major upgrade of the ATLAS National User Facility. The overall project will dramatically increase the beam current available for the stable ion beam research program, increase the beam intensity for neutron-rich beams from Californium Rare Isotope Breeder Upgrade (CARIBU) and improve the intensity and purity of the existing in-flight rare isotope beam (RIB) program. The project will take place in two phases. The first phase is fully funded and focused on increasing the intensity of stable beams by a factor of 10. This will be done using a new normal conducting, CW RFQ accelerator and replacing three cryostats of split-ring resonators with a single new cryostat of high-performance quarter-wave resonators. To further increase the intensity for neutron-rich beams, we have started development of a high-efficiency charge breeder for CARIBU based on an Electron Beam Ion Source. The goal of the proposed second phase will be to increase the energies and intensities of stable beams, as well as, increase the efficiency and beam current for CARIBU and in-flight RIB beams. The focus of this paper is on innovative developments for Phase I of the project.

 
MOP046 Status and Plans for the Facility for Rare Isotope Beams at Michigan State University linac, ion, cryomodule, target 160
 
  • R.C. York, G. Bollen, M. Doleans, W. Hartung, M.J. Johnson, G. Machicoane, F. Marti, X. Wu, Q. Zhao
    NSCL, East Lansing, Michigan
  • S. Assadi, T . Glasmacher, E. Pozdeyev, E. Tanke
    FRIB, East Lansing, Michigan
 
 

The primary purpose of the Facility for Rare Isotope Beams (FRIB) is to produce and to do fundamental research with rare isotopes. The rare isotope production will be accomplished using a heavy ion cw linac to provide a stable isotope beam (protons through uranium) at high power (up to 400 kW) and high energy (>200 MeV/u) on a particle fragmentation production target. The rare isotopes will be produced in quantities sufficient to support world-leading research by using particle fragmentation of stable beams. This will include research pertaining to the properties of nuclei (nuclear structure), the nuclear processes in the universe and tests of fundamental symmetries. Societal applications and benefits may include bio-medicine, energy, material sciences and national security. The overall facility status and plans will be discussed with a focus on the accelerator system.

 
MOP048 Experimental Study of the Surface Resistance of the 141 Mhz Quarter-Wave Resonator at Triumf ISAC, vacuum, TRIUMF, monitoring 166
 
  • D. Longuevergne
    UBC & TRIUMF, Vancouver, British Columbia
  • C.D. Beard, A. Grassellino, P. Kolb, R.E. Laxdal, V. Zvyagintsev
    TRIUMF, Vancouver
 
 

The upgrade (Phase II) of the ISAC-II superconducting linac has been completed this spring and has been commissioned. Two spare 141 MHz Quarter-Wave Resonators made of bulk Niobium are available at TRIUMF to lead more specific studies on surface resistance. This opportunity has also been taken to optimize the surface treatment to improve the accelerating field gradient at the operating power level. The aim of the study presented here is to link together several surface treatments (etching depth, 120C baking) and test conditions (Q-disease, 4.2 K and 2K tests) and sequence them in an appropriate order to understand more deeply their dependencies.

 
MOP049 Electro-Magnetic Optimization of a Quarter-Wave Resonator cryomodule, solenoid, rfq, booster 169
 
  • B. Mustapha, P.N. Ostroumov
    ANL, Argonne
 
 

A new cryomodule is being designed for the ongoing ATLAS efficiency and intensity upgrade. The cryomodule consists of 7 Quarter-Wave Resonators (QWR) with β-G=0.075 and 4 SC solenoids to replace the existing split-ring cavities. To reduce the resonator frequency jitter due to micro-phonics we choose a frequency of 72.75 MHz instead of 60.625 MHz. At 72.75 MHz, the cavity is shorter by about 20 cm. The choice of the design β was optimized based on the beam dynamics and the actual performance of ATLAS cavities. To reach a record high accelerating voltage of 2.5 MV per cavity or higher, the EM design was carefully optimized. The main goal of the optimization was to minimize the peak magnetic and electric fields while still keeping good values for the stored energy, the shunt impedance (R/Q) and the geometric factor (Rs/Q). The cavity height was also another important parameter. The optimization has lead to a final shape which is cylindrical in the bottom and conic on the top keeping a high real-estate gradient. The optimization also included the internal drift tube face angle required for beam steering correction.

 
MOP051 RF Power Tests and Results of the First Rebuncher for the SPIRAL 2 Driver impedance, coupling, resonance, simulation 172
 
  • M. Lechartier, D. Besnier, R. Beunard, J.F. Leyge, M. Michel, P. Robillard, P. Toussaint
    GANIL, Caen
 
 

Three normal conducting rebunchers are located in the MEBT line of the SPIIRAL2 driver.  The cavity are designed for a beta of 0.04, work at 88 MHz and have to supply beam voltages up to 120 kV in continuous mode or up to 190 kV in  pulsed mode with 50%dutycycle. The  paper describes the  RF measurements and first results

 
MOP053 Testing of Super Conducting Low-beta 704 MHz Cavities at 50 Hz Pulse Repetition Rate in View of SPL - First Results* klystron, controls, feedback, simulation 175
 
  • W. Höfle, M. Hernandez Flano, J. Lollierou, D. Valuch
    CERN, Geneva
  • S. Chel, M. Desmons, G. Devanz, O. Piquet
    CEA, Gif-sur-Yvette
  • R. Paparella, P. Pierini
    INFN/LASA, Segrate (MI)
 
 

In the framework of the preparatory phase for the luminosity upgrade of the LHC (SLHC-PP ) it is foreseen to characterize two superconducting RF cavities and demonstrate compliance of the required SPL field stability in amplitude and phase using a prototype LLRF system. We report on the preparation for testing of two super-conducting low-beta cavities at 50 Hz pulse repetition rate including the setting-up of the low level RF control system to evaluate the performance of the piezo-tuning system and cavity field stability in amplitude and phase. Results from tests with 50 Hz pulse repetition rate are presented. Simulations of the RF system are used to predict the necessary specifications for power and bandwidth to control the cavity field and derive specifications for the RF system and its control.


This project has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under the Grant Agreement no 212114

 
MOP055 A CW SRF Linac to Drive Subcritical Nuclear Reactors proton, linac, SRF, neutron 178
 
  • M. Popovic
    Fermilab, Batavia
  • C.M. Ankenbrandt, R.P. Johnson
    Muons, Inc, Batavia
 
 

In the last 20 years, superconducting RF (SRF) cavities have been developed to the point that a CW SRF linac is the best candidate driver for subcritical reactors. We discuss how one appropriately designed linac can be used for an accelerator-driven subcritical (ADS) nuclear power station to produce more than 5 GW electrical power in an inherently safe region below criticality. Such a station will generate no greenhouse gases, produce minimal nuclear waste and no byproducts that are useful to rogue nations or terrorists, incinerate waste from conventional nuclear reactors, and efficiently use abundant thorium fuel that does not need enrichment. We describe the Linac parameters that can enable this vision of an almost inexhaustible source of power and we discuss how the corresponding reactor technology can be matched to these parameters.

 
MOP056 Status of the ALPI Low-beta Section Upgrade linac, acceleration, vacuum, rf-amplifier 181
 
  • A. Facco, P. Modanese, F. Scarpa
    INFN/LNL, Legnaro (PD)
  • Y. Ma
    CIAE, Beijing
 
 

The low-beta section of the ALPI linac at Laboratori Nazionali di Legnaro is being upgraded in order to double its energy gain from about 10 MV to 20 MV. This upgrade, performed with a rather limited investment in the background of the standard accelerator activities, is based on the replacement of some rf system components and minor modifications to the cryostats. The cavities, working at 80 MHz, require a 3 dB rf bandwidth of 15 Hz (obtained by means of strong overcoupling) to be locked in the presence of the large Helium pressure fluctuations of ALPI. Their average gradient, although exceeding 6 MV/m at the nominal 7 W power, is presently kept around 3 MV/m during operation, limited by the maximum available rf power in the linac. The ongoing upgrade requires the modification of all low-beta cryomodules to allow new, liquid Nitrogen cooled rf couplers and new, 1 kW amplifiers. A fully equipped prototype cryostat with four, beta=0.047 QWRs has been constructed and tested on line, and operated at 6 MV/m reaching or exceeding all the design goals. The test results will be reported and discussed and the project status will be presented.

 
MOP057 A CW Operated Superconducting Heavy Ion CH-Type Linac for Super-Heavy Element Research at GSI linac, heavy-ion, ion, solenoid 184
 
  • H. Podlech, M. Amberg, M. Busch, F.D. Dziuba, U. Ratzinger, R. Tiede
    IAP, Frankfurt am Main
  • W.A. Barth, S. Mickat
    GSI, Darmstadt
 
 

The search for Super-Heavy Elements (SHE) is one of the frontiers in nuclear physics. By trend the production cross sections decrease significantly for larger proton numbers and heavier nuclei, respectively. To limit the required beam time it is necessary to use the highest available intensity. This prefers cw operation and the use of superconducting cavities. A cw operated superconducting linac using CH-cavities at GSI has been designed. As front end the existing 108 MHz High Charge Injector (HLI) will be used which is presently being upgraded for cw operation. The superconducting part of the linac covers the energy between 1.4 AMeV and 7.5 AMeV. It consists of 9 multi-cell CH-cavities operated at 217 MHz. Each cavity is optimized for a specific particle velocity but without beta profile. Above 3.5 AMeV the linac is fully energy variable. The first superconducting CH-cavity is already under construction and will be tested with beam delivered by the HLI. The talk covers the development of the prototypes and the overall design including beam dynamics issues.

 
MOP071 The Hot Prototype of the PI-Mode Structure for Linac4 linac, coupling, proton, vacuum 220
 
  • F. Gerigk, P. Bourquin, A. Dallocchio, G. Favre, J.-M. Geisser, L. Gentini, J.-M. Giguet, S.J. Mathot, M. Polini, D. Pugnat, B. Riffaud, S. Sgobba, T. Tardy, P. Ugena Tirado, M. Vretenar, R. Wegner
    CERN, Geneva
 
 

The PIMS cavities for Linac4 are made of 7 coupled cells operating in pi-mode at 352 MHz frequency. The mechanical concept is derived from the 5-cell cavities used in the LEP machine, whereas cell length and coupling are adapted for proton acceleration in the range from 50 to 160 MeV. Linac4 will be the first machine to employ this type of cavities for low-beta protons. During the first years of operation the PIMS will be used at low duty cycle as part of the consolidated LHC proton injector complex. It is designed, however, to operate eventually in a high duty cycle (10%) proton injector, which could be used as proton front-end for neutrino or RIB applications. To prepare for the series construction of the 12 PIMS units the first cavity (102 MeV beam energy) has been designed and constructed at CERN, to be used as a hot prototype for RF tests and as a pre-series mechanical unit. In this paper we report on some of the design features, the construction experience, and first measurements.

 
MOP076 An Experimental Investigation on Cavity Pulsed Heating site, damping, feedback, vacuum 232
 
  • L. Laurent, V.A. Dolgashev, C.D. Nantista, S.G. Tantawi
    SLAC, Menlo Park, California
  • M. Aicheler, S.T. Heikkinen, W. Wuensch
    CERN, Geneva
  • Y. Higashi
    KEK, Ibaraki
 
 

Cavity pulsed heating experiments have been conducted at SLAC National Accelerator Laboratory in collaboration with CERN and KEK. These experiments were designed to gain a better understanding on the impact of high power pulsed magnetic fields on copper and copper alloys. The cavity is a one port hemispherical cavity that operates in the TE013-like mode at 11.424 GHz. The test samples are mounted onto the endcap of the cavity. By using the TE013 mode, pulsed heating information can be analyzed that is based only on the impact of the peak magnetic field which is much bigger in value on the test sample than on any other place in the cavity. This work has shown that pulsed heating surface damage on copper and copper alloys is dependent on processing time, pulsed heating temperature, material hardness, and crystallographic orientation and that initial stresses occur along grain boundaries which can be followed by pitting or by transgranular microfractures that propagate and terminate on grain boundaries. The level of pulsed heating surface damage was found to be less on the smaller grain samples. This is likely due to grain boundaries limiting the propagation of fatigue cracks.

 
MOP077 Design of RF Feed System for Standing-wave Accelerator Structures coupling, wakefield, vacuum, acceleration 235
 
  • J. Neilson, V.A. Dolgashev, S.G. Tantawi
    SLAC, Menlo Park, California
 
 

Typical surface damage in travelling wave accelerator structures occurs on the high field region of the iris. As the damage accumulates the coupling between cavities is affected resulting in changes in the phase shift between cells. This issue can be reduced by use of SW cells that are fed in parallel. RF breakdown is contained to the cell where it originates and the available electromagnetic energy for a given gradient is minimized by the parallel feed. Several schemes[1] have been proposed for parallel fed SW structures. Some of the proposed designs fed several cells from each arm, which reduces the advantage of localizing a RF breakdown to an individual cavity. In addition they use a standing wave in the feed arms which allows coupling between cells. We are proposing a somewhat more complex approach using a directional coupler on each cell and serpentine waveguide connection between couplers. This design approach isolates the cells and gives an individual rf feed to each cell resulting in the maximum increase in the operational robustness of the accelerator structure.


1. O. N. Brezhnev, P. V. Logatchev, V. M. Pavlov, O. V. Pirogov, S. V. Shiyankov,' Parallel-Coupled Accelerating Structures', Proceedings of LINAC 2002, Gyeongju, Korea, pg 215-217

 
MOP080 Design Optimisation of the Re-bunching Cavities for the Front End Test Stand at RAL impedance, simulation, bunching, rfq 238
 
  • D.C. Plostinar
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • R. Enparantza, M. Larrañaga
    Fundación TEKNIKER, Eibar (Gipuzkoa)
 
 

The Medium Energy Beam Transport (MEBT) line for the Front End Test Stand (FETS) at Rutherford Appleton Laboratory (RAL) will transport a 60 mA, 2ms, 50 pps H- beam at 3 MeV. Its main components include a number of quadrupoles, re-bunching cavities and a fast-slow chopping system with dedicated beam dumps, as well as a diagnostics beam line. In this paper we present the design approach for the MEBT re-bunching cavities. A description is given for the proposed geometry and the main design choices are examined. In addition, the latest RF simulations results performed with 2D and 3D electromagnetic codes are presented including optimisation details and manufacturing plans.

 
MOP081 The PITZ CDS Booster Cavity RF Tuning and Start of Conditioning booster, vacuum, coupling, electron 241
 
  • V.V. Paramonov, A. Naboka
    RAS/INR, Moscow
  • A. Donat, L. Jachmann, W. Köhler, M. Krasilnikov, J. Meissner, D. Melkumyan, M. Otevrel, B. Petrosyan, J. Schultze, F. Stephan, G. Trowitzsch, R.W. Wenndorff
    DESY Zeuthen, Zeuthen
  • K. Flöttmann
    DESY, Hamburg
  • D. Richter
    HZB, Berlin
 
 

The DESY PITZ booster cavity, based on the Cut Disk Structure (CDS), is completed in construction. The L-band normal conducting cavity is intended to operate with accelerating rate up to 12.5 MV/m and RF pulse length up to 800 mks to increase the electron bunch energy in the PITZ facility at 20 MeV. The cavity was vacuum conditioned to reduce the out-gassing rate for operation in the facility with photo cathodes. The cavity is mounted in the PITZ tunnel and RF conditioning is started. The results of RF tuning before and after cavity brazing, together with first results of conditioning, are presented.

 
MOP082 Low Level Radio-frequency Developments toward a Fault-tolerant Linac Scheme for an Accelerator Driven System LLRF, linac, simulation, controls 244
 
  • F.B. Bouly, J.-L. Biarrotte, C. Joly
    IPN, Orsay
 
 

An Accelerator Driven System (ADS) for transmutation of nuclear waste requires a high power proton beam (several MWs) to reach the necessary spallation efficiency. Due to the induced thermal stress to the subcritical core, the high-power proton linac will have to fulfil stringent reliability requirements to minimise the number of unwanted beam trips (> 1 sec.) per operation cycle. In view of the construction of the MYRRHA ADS demonstrator, in Mol (Belgium), beam dynamic analyses were carried out to evaluate the fault tolerant capability of the superconducting linac, in the particular case of a radiofrequency (RF) cavity failure. This analysis was coupled with simulations on the RF behaviour of 700 MHz superconducting cavitiy as well as its tuning and feedback loop systems. Such considerations led to the development of a prototypical digital Low Level RF (LLRF) system to control the cavity phase and accelerating field, especially in the case of fast cavity retuning for failure compensation. In this paper we summarize the work which has been performed so far toward the development of such a fault-tolerant RF linac.

 
MOP083 LLRF Design for the HINS-SRF Test Facility at Fermilab LLRF, resonance, SRF, controls 247
 
  • J. Branlard, B. Chase, E. Cullerton, P.W. Joireman, V. Tupikov
    Fermilab, Batavia
 
 

The High Intensity Neutrino Source (HINS) R&D program requires super conducting single spoke resonators operating at 325 MHz. After coupler installation, these cavities are tested at the HINS-SRF facility at Fermilab. The LLRF requirements for these tests include support for continuous wave and pulsed mode operations, with the ability to track the resonance frequency of the tested cavity. Real-time measurement of the cavity loaded Q and Q0 are implemented using gradient decay techniques, allowing for Q0 versus Eacc plots. A real time cavity simulator was also developed to test the LLRF system and verify its functionality.

 
MOP084 A Vector Control and Data Acquisition System for the Multicavity LLRF System for Cryomodule1 at Fermilab controls, LLRF, cryomodule, feedback 250
 
  • P. Varghese, B. Barnes, J. Branlard, B. Chase, E. Cullerton, P.W. Joireman, V. Tupikov
    Fermilab, Batavia
 
 

A LLRF control and data acquisition system for the 8-cavity Cryo-Module 1 at the ILCTA has been implemented using three , 33-channel MFC boards in a VXI mainframe. One card each is dedicated for the cavity probes for vector control , forward power and reverse power measurements. The system is scalable to 24 cavities or more with the commissioning of Cryo-Modules 2 and 3 without additional hardware. The signal processing and vector control of the cavities is implemented in a FPGA and a high speed data acquisition system with upto 100 channels stores data in external SDRAM memory. The system supports both pulsed and CW modes with a pulse rate of 5Hz. Acquired data is transferred between pulses to auxiliary systems such as the piezo controller through the slot0 controller. The design of the system is described and the performance of the vector control system is evaluated.

 
MOP086 Stability Evaluation for Long FB Loop Delay in the ACS Cavity Field Control for the J-PARC Linac 400-MeV Upgrade controls, linac, klystron, simulation 253
 
  • T. Kobayashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
 

For 400-MeV upgrade of the J-PARC Linac, ACS (Annular Coupled Structure) cavities, which are driven by 972-MHz RF, will be installed. The ACS cavity has complicated structure. Its Q-value is very low and the operation frequency is tree times higher in comparison with that of the SDTL cavity. So the stabilizing control of the ACS accelerating field will be more difficult than present 324-MHz RF system. Further more the chopped beam loading compensation is required. Especially, the debuncher will be located very far from the klystron, then the feedback loop delay will be about 1.5 us. This presentation will show the simulation results of the feedback control of the ACS cavity field including long loop delay and the effect of the chopped beam loading.

 
MOP087 Beam Test of Chopped Beam Loading Compensation for the J-PARC Linac 400-MeV Upgrade beam-loading, linac, controls, LLRF 256
 
  • T. Kobayashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • M. Ikegami
    KEK, Ibaraki
 
 

The function of the chopped beam loading compensation was implemented into the digital feedback/feed-forward control system of the J-PARC Linac LLRF system to stabilize the ACS cavity fields for the 400-MeV upgrade. The beam test of the chopped beam loading compensation was performed with the present 324-MHz cavity sysmte. Consequently the chopped beam loading was successfully compensated and that this system is valid.

 
MOP089 Spallation Neutron Source High-Power Protection Module Test Stand controls, neutron, LLRF, linac 262
 
  • S.W. Lee, J.A. Ball, T.L. Davidson, S.L. Jones
    ORNL RAD, Oak Ridge, Tennessee
  • M.T. Crofford, T.W. Hardek
    ORNL, Oak Ridge, Tennessee
 
 

The Spallation Neutron Source (SNS) High-Power Protection Module (HPM) provided interlocks and fast shutdown for the RF system to protect the accelerating structures and high power RF (HPRF) Distribution System. The HPM has required some functionality upgrades since the start of beam operations and an upgrade to the HPM test stand was required to support these added features. The HPM test stand currently verifies functionality, RF channel calibration, and measurement of the speed of shutdown to ensure the specifications are meet. The upgraded test stand was implemented in a single FPGA to allow for future growth and flexibility. Work is currently progressing on automation of the test stand to better perform the required module calibration schedule.

 
MOP090 Design and Testing of the TRIUMF ISACII High-B RF Control System controls, TRIUMF, linac, cryomodule 265
 
  • M.P. Laverty, K. Fong, R.E. Laxdal, Q. Zheng
    TRIUMF, Vancouver
  • G. Dennison
    UBC & TRIUMF, Vancouver, British Columbia
 
 

The rf control system for the twenty 141 MHz TRIUMF quarter wave superconducting cavities is a hybrid analogue/digital design. It is based in part on an earlier design developed for the 106MHz 1/4 wave superconducting cavities of the ISACII linac. This design has undergone several iterations in the course of its development. In the current version, a value-engineering approach was used to reduce the cost and simplify the hardware. The result is a single C-size VXI module that incorporates all the required low-level rf functions - amplitude/phase control, tuning control, and control of the rf coupler. It accomplishes these functions at a substantially lower cost than the previous two-module solution. It also includes support for field upgrade of the DSP/PLD hardware and firmware. Some early test results of the system operating in the linac are outlined, and conclusions are summarized.

 
MOP091 A Digital Low Level RF Control System for the S-DALINAC controls, low-level-rf, superconducting-cavity, electron 268
 
  • M. Konrad, U. Bonnes, C. Burandt, R. Eichhorn, N. Pietralla
    TU Darmstadt, Darmstadt
 
 

The superconducting cavities of the S-DALINAC have a high loaded quality factor and are very susceptible to microphonics. To stabilize the amplitude and phase of the cavities' fields an analog control system has been used for 20 years. To improve the stability and the availability of the low level RF control system it is currently replaced by a digital one. The 3 GHz signals coming from the cavities are converted down to the base band using hardware I/Q demodulators. The base band signals are digitized by ADCs and fed into an FPGA. This FPGA contains a custom CPU which executes the code implementing the control algorithm. The computed control signal is I/Q modulated before it is send to the cavity again. The superconducting cavities are operated with a self-excited loop algorithm whereas a generator driven algorithm is used for the low Q normal conducting bunching cavities. A 6 GHz RF board allows the operation of a new 2f buncher. Parameters can be adjusted via an EPICS IOC running on a standard PC. All signals from the FPGA can be monitored in realtime by the operator.

 
MOP093 Design of Low Level RF Control System for Accelerator controls, LLRF, superconducting-cavity, emittance 274
 
  • Y.S. Lee, J.-S. Chai
    SKKU, Suwon
  • K.R. Kim, K.-H. Park
    PAL, Pohang, Kyungbuk
 
 

The low level RF (LLRF) control system for PLS is being upgraded to improve the performance of the system. The LLRF control system under development consists of FPGA, and high speed ADC and DAC as well as analog front-end devices which process the signal from cavity and to RF high power system. In addition, it utilizes digital signal processing technology based on FPGA. In order to optimize the accelerating electric field in the cavity, it is required to maintain field stability less than ±1% in amplitude and 1° in phase. And the resonance condition of the cavity should be monitored and controlled. The various digital signal processing theories such as digital filters, Cordic, PI control enable to meet these requirements and to control the feedback signal less than a microsecond. The LLRF control system is also equipped with the Ethernet by the cPCI. The preliminary design study on the LLRF control system for PLS superconducting cavity will be described in this paper.

 
MOP094 Cavity Control Algorithms controls, feedback, LLRF, radio-frequency 277
 
  • T. E. Plawski, C. Hovater
    JLAB, Newport News, Virginia
 
 

A digital low level radio frequency (RF) system typically incorporates either a heterodyne or direct sampling technique, followed by fast ADCs, then an FPGA, and finally a transmitting DAC. This universal platform opens up the possibilities for a variety of control algorithm implementations. The foremost concern for an RF control system is cavity field stability, and to meet the required quality of regulation, the chosen control system needs to have sufficient feedback gain. In this paper we will investigate the effectiveness of the regulation for three basic control system algorithms: I&Q (In-phase and Quadrature), Amplitude & Phase and digital SEL (Self Exciting Loop) along with the example of the Jefferson Lab 12 GeV cavity field control system.

 
MOP095 Status of the CEBAF Energy Upgrade RF Control System controls, LLRF, interlocks, EPICS 280
 
  • C. Hovater, T.L. Allison, R. Bachimanchi, G.E. Lahti, J. Musson, T. E. Plawski, C. Seaton, D.J. Seidman
    JLAB, Newport News, Virginia
 
 

To support the CEBAF energy upgrade from 6 GeV to 12 GeV, the RF control system is being modernized to control the high gradient high QL superconducting cavities. The new system incorporates a heterodyne transceiver along with I&Q sampling to measure and control magnitude and phase. A low-cost Altera FPGA is used to digitally implement the cavity control algorithms. One of the features of the system is a digital self excited loop to track the cavity over large Lorentz detuning (800 Hz) during turn on. The system has successfully completed preliminary development and is now moving into the production stage of the project. This paper discusses the design, modeling, testing and production of the new RF control system and associated peripheral systems (cavity interlocks, and resonance control).

 
MOP099 Status of the Design of 650 MHz Elliptical Cavities for Project X linac, proton, beam-losses, coupling 289
 
  • S. Barbanotti, M.H. Foley, I.G. Gonin, J. Grimm, T.N. Khabiboulline, L. Ristori, N. Solyak, V.P. Yakovlev
    Fermilab, Batavia
 
 

Project X is a proposed high-intensity proton accelerator complex that could provide beam to create a high-intensity neutrino beam, feed protons to kaon- and muon-based precision experiments, and for other applications still under investigation. The present configuration of the proton accelerator foresees a section with 650 MHz beta = 0.6 and beta = 0.9 elliptical cavities. Prototypes of single-cell 650 MHz cavities and five-cell beta = 0.9 650 MHz cavities are being designed and fabricated at Fermilab in the R&D process for Project X. This paper summarizes the design status of the beta = 0.6 and beta = 0.9 single-cell prototype cavities, and also addresses the design effort focused on the five-cell beta = 0.9 cavities.

 
MOP101 Rebuncher Cavities for the FRANZ Bunch Compressor impedance, neutron, linac, proton 295
 
  • D. Noll, L.P. Chau, M. Droba, O. Meusel, H. Podlech, U. Ratzinger
    IAP, Frankfurt am Main
 
 

The Frankfurt Neutron Source (FRANZ) currently under construction at IAP (Goethe University of Frankfurt) is designed to produce short neutron pulses at high intensity and repetition rates up to 250 kHz [*]. To achieve a bunch length of one nanosecond despite the high space charge forces, a bunch compressor of the Mobley type [**] using four dipole magnets and two rebunchers has been developed [***] to merge 9 linac bunches into the final focus. The first rebuncher cavity, a λ/4 resonator operating at 87.5 MHz, has to feature nine beam paths due to the multi-trajectory system. Additionally the gaps have to be displaced relatively to each other in a way that all bunches arrive at the correct rf phase. The second rebunching cavity will provide final focusing as well as an energy variation of ±0.2 MeV in front of the target and will be operating at 175 MHz. This paper presents the design of these novel cavities as well as the simulated beam dynamic properties.


* Meusel et al., LINAC 2006
** Mobley, Phys. Rev. 88(2), 360-361 (1951)
*** Chau et al, LINAC 2010

 
MOP103 Studies on High-precision Machining and Assembly of CLIC RF Structures simulation, damping, alignment, collider 301
 
  • J. Huopana
    HIP, University of Helsinki
  • S. Atieh, G. Riddone
    CERN, Geneva
  • K. Österberg
    Helsinki University, Department of Physics, University of Helsinki
 
 

The Compact Linear Collider (CLIC) is currently under development at CERN as a potential multi-TeV e+e' collider. The manufacturing and assembly tolerances for the required RF components are essential for the final efficiency and for the operation of CLIC. The proper function of an accelerating structure is sensitive to mechanical errors in the shape and the alignment of the accelerating cavity. The current tolerances are in the micron range. This raises challenges in the field of mechanical design and demands special manufacturing technologies and processes. Currently the mechanical design of the accelerating structures is based on a disk design. Alternatively, it is possible to create the accelerating assembly from quadrants, which has the potential to be favoured for the mass production due to simplicity and cost. In this case, the functional shape inside of the accelerating structure remains the same and a single assembly uses less parts. This paper focuses on the development work done in design and simulation for prototype accelerating structures and describes its application to series production.

 
MOP106 Implementation of Multilayered Conductor Structures on RF Cavity Surfaces resonance, vacuum, linac, controls 310
 
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto
 
 

Multilayered conductor structures on RF cavity surfaces have been discussed these years. Although a real implementation was succeeded on a coaxial cavity at room temperature by measuring Q-value, it may not be a practical example. Application of the multilayered conductor structure on superconducting cases came out recently and is studied by some groups. Possible thoughts on the further implementation at room temperature will be discussed including a consideration on the superconducting case.

 
MOP113 Multipacting Simulation of the Demountable Damped Cavity simulation, electron, HOM, coupling 328
 
  • T. Konomi
    Sokendai, Ibaraki
  • F. Furuta, K. Saito
    KEK, Ibaraki
 
 

We have designed Demountable Damped Cavity (DDC) as an ILC R&D. DDC has an axial symmetric structure, the coaxial waveguide HOM coupler and absorber at the end of beam pipe of SRF cavity. It is also demountable structure. These structures are expected to bring better cavity performance. However, DDC have many parallel faced surfaces and the multipacting might be a concerned issue. We have simulated MP on the DDC with CST-Studio and found MP could be not serious issue. In this paper we will report the simulation result in detail.

 
MOP114 Confirmation of Leak Tightness of the Mo Sealing in Superfluid Helium vacuum, SRF, impedance, pick-up 331
 
  • K. Saito, F. Furuta
    KEK, Ibaraki
  • T. Konomi
    Nagoya University, Nagoya
 
 

MO sealing developed by Prof. H. Matsumoto in KEK and his collaborator M. Ohotsuka has been successfully applied to SRF cavities. Its leak ratio is smaller than 3·10-8 Pam3/s or much better in the superfluid Helium, which is the allowed level to successfully measure the cavity performance for more than 3 hours at 2K. Tightening torque is 15Nm and the bolt material is SUS304 (JIS). Titanium is usable as cavity flange material. Copper looks better than pure Aluminium as the gasket material. We have observed an additional residual surface resistance about 5nΩ Zero impedance characteristics of the MO sealing is a remained issue. In this paper we report the results in detail.

 
TU201 Status of J-PARC Linac Energy Upgrade linac, coupling, klystron, injection 357
 
  • H. Ao
    JAEA/LINAC, Ibaraki-ken
 
 

The J-PARC (Japan Proton Accelerator Research Complex) accelerator comprises the 400-MeV injector linac (at present 181 MeV), the 3-GeV Rapid-Cycling Synchrotron (RCS) and the 50-GeV Main Ring (MR). The 3-MeV RFQ, the 50-MeV DTL and the 181-MeV Separated-type DTL have been operated in the linac for experimental users. The 400-MeV energy upgrade of the linac started from March 2009. The ACS (Annular Coupled Structure) cavities, the RF sources, the beam monitors and the utilities are in production. Although some components are prepared in the annual summer shutdown separately, the all cavities will be installed and commissioned for 6 months from July 2012. In this paper, we present the current status and the preliminary results of the energy upgrade.

 
TU203 Plans for the ESS Linac linac, cryomodule, controls, emittance 367
 
  • S. Peggs, M. Eshraqi, H. Hahn, A. Jansson, M. Lindroos, A. Ponton, K. Rathsman, C.G. Trahern
    ESS, Lund
  • S. Bousson
    IPN, Orsay
  • R. Calaga
    BNL, Upton, Long Island, New York
  • H. Danared
    MSL, Stockholm
  • G. Devanz, R.D. Duperrier
    CEA, Gif-sur-Yvette
  • J. Eguia
    Fundación TEKNIKER, Eibar (Gipuzkoa)
  • S. Gammino
    INFN/LNS, Catania
  • S.P. Møller
    ISA, Aarhus
  • C. Oyon
    SPRI, Bilbao
  • R.J.M.Y. Ruber
    Uppsala University, Uppsala
  • T. Satogata
    JLAB, Newport News, Virginia
 
 

Following selection of Lund as the site for the long-pulse ESS (European Spallation Source), a team of accelerator and target experts has been working on an update of the 2003 ESS linac design. Improvements to the 2003 design will be summarised, and the latest designs for the linac will be presented.

 

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TU302 Applications of Spoke Cavities linac, ion, superconducting-cavity, coupling 377
 
  • J.R. Delayen
    ODU, Norfolk, Virginia
 
 

Review of the theory, design and applications of Spoke cavities, with particular emphasis on SRF spoked cavities. Aspects of low level RF control for spoke cavities will also be presented.

 

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TU303 Status of the Cornell ERL Injector Cryomodule HOM, cryomodule, SRF, alignment 382
 
  • M. Liepe
    CLASSE, Ithaca, New York
 
 

The Cornell Energy Recovery Linac (ERL) Injector cryomodule is part of a prototype electron beam source to demonstrate production of CW 1.3 GHz, 100 mA average current, 2 ps, 77 pC bunches with emittance of 1 mm-mrad. After a successful initial run of the cryomodule with beam, an improvement program was initiated in the Fall 2009. The goals of the reconfiguration were to replace the RF absorbers in the beamline HOM loads that were subject to static charging, re-process the SRF cavities that exhibited a low Q that further decreased by 50% during the run, and improve diagnostic sensor accuracy within the cryomodule. The upgraded cryomodule was re-commissioned in early 2010 with excellent performance. Details of the investigation and remedies for HOM load charging, cavity Q recovery, and module assembly logistics will be presented along with the ERL Injector beam performance.

 

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TU304 High-Performance SC Cryomodule for CW Ion Accelerators linac, cryomodule, ion, niobium 387
 
  • M.P. Kelly
    ANL, Argonne
 
 

Recent developments for cryomodules required for various low- and medium beta- CW ion accelerator projects will be presented. Comparisons of the designs, fabrication technology and assembly procedures of cryomodules will be discussed. To date, development in this area has been mostly for basic science applications, however, there is also considerable interest in ion accelerators for other applications such as national defense, medicine and accelerator driven systems. The outlook for and some development requirements of SRF cryomodules for these applications will be discussed.

 

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TUP001 Conceptual Design of the C-Band Module for SwissFEL klystron, wakefield, linac, coupling 392
 
  • R. Zennaro, J. Alex, M. Bopp, H.-H. Braun, A. Citterio, H. Fitze, M. Pedrozzi, J.-Y. Raguin
    PSI, Villigen
 
 

The Swiss FEL linac consists of a 450 MeV S-band injector and of a main linac at the C-band frequency (5.712 GHz) aiming at a final energy of 5.8 GeV. The main linac is composed of 26 RF modules. Each module consists of a single 50 MW klystron and its solid-state modulator feeding a pulse compressor and four accelerating structures. The two-meter long C-band accelerating structures have 110 cells, including the two coupler cells, and operate with a 2π/3 phase advance. We report here on RF studies performed on the accelerating structures with different cell topologies and on the pulse compressor where a Barrel-Open Cavity (BOC) design is adopted. The power requirements for the different accelerating structures with the single and two-bunch operation are also presented.

 
TUP004 Status of ERL and cERL Projects in Japan gun, laser, electron, klystron 398
 
  • S. Sakanaka, H. Kawata, Y. Kobayashi
    KEK, Ibaraki
  • R. Hajima
    JAEA/ERL, Ibaraki
  • N. Nakamura
    ISSP/SRL, Chiba
 
 

Future light sources based on the Energy Recovery Linac (ERL) are expected to bring innovation to the synchrotron radiation (SR) science. Our Japanese collaboration team plans to construct a 5-GeV ERL which can produce super-brilliant and ultra-short pulses of SR as well as can be a driver for a proposed X-ray free-electron laser oscillator (X-FELO). In order to establish the key technologies for the ERL, we are conducting aggressive R&D efforts. Concerning our high-brightness photocathode DC electron gun, we succeeded to apply a DC high voltage of 500 kV through a support rod. Both cryomodules for the injector and the main-linac are also under development. In order to demonstrate reliable operations of such key technologies, we plan to construct the Compact ERL (cERL) at KEK. During FY2009, we prepared the infrastructure for the cERL which includes renovation of the building (the East Counter Hall), renovation of cooling-water system and electrical substation, installation of liquid helium refrigerator, and installation of a part of the rf source. In this paper, we present up-to-date status of the ERL and the Compact ERL projects in Japan.

 
TUP005 Status of Development of the cERL Superconducting Injector Linac HOM, pick-up, linac, target 401
 
  • K. Watanabe, E. Kako, S. Noguchi, M. Satoh, T. Shishido, Y. Yamamoto
    KEK, Ibaraki
 
 

Development of the superconducting injector Linac for compact ERL has been continuing at KEK. The cryomodule including three two-cell SC cavities was designed. Two prot-type two-cell cavities were fabricated, and the vertival test were carried out after the standard surface preparation at STF. The high power tests of the input couplers were also carried out at the test stand with 300 kW cw klystron. The status of the cERL injector cryomodue will be reported.

 
TUP006 Development of a Main Linac Module for Compact ERL Project HOM, linac, cryomodule, superconducting-cavity 404
 
  • K. Umemori, T. Furuya, H. Sakai, T. Takahashi
    KEK, Ibaraki
  • M. Sawamura
    JAEA/ERL, Ibaraki
  • K. Shinoe
    ISSP/SRL, Chiba
 
 

A construction of the Compact ERL is planned in KEK, Japan. A demonstration of the performance of the main linac super-conducting accelerating system is one motivation of the project. We have been designing a cryo-module, which works under CW operation, and contains two 9-cell cavities, with input couplers, frequency tuners and HOM dampers. Most of these components have been specially developed for ERL operation. Two proto-type of the 9-cell cavity were constructed. First one was vertically tested and suffered from field emissions. Second one is now waiting a measurement. High power component tests have been carried out for input coupler. At first, large temperature rise was observed at a ceramic window part due to unexpected dipole resonance. After that, new version of window was designed and successfully passed 20kW CW power with reflection. Proto-types of HOM damper were also constructed. Cooling tests have been performed for them to verify cooling ability against more than 100W heat load, under vacuum condition. A cryo-module will be completed in 2012, and cooling tests and beam tests will follow.

 
TUP007 BERLinPro - A Compact Demonstrator ERL for High Current and Low Emittance Beams linac, emittance, SRF, gun 407
 
  • J. Knobloch, M. Abo-Bakr, W. Anders, A. Jankowiak, T. Kamps, O. Kugeler, B.C. Kuske, P. Kuske, A.N. Matveenko, A. Meseck, A. Neumann, T. Quast, J. Rudolph
    HZB, Berlin
 
 

Energy recovery linacs (ERLs) are proving to be a powerful option to provide very high current beams with exceptional beam parameters and the flexibility to tailor these for many applications, from next-generation light sources to electron coolers. Helmholtz Zentrum Berlin (HZB) is focusing on ERLs for future x-ray light sources. Although ERL facilities exist for the IR and THz range, their moderate parameters (current, emittance, energy) are insufficient for future x-ray sources. HZB is therefore proposing to develop the 100-MeV ERL facility BERLinPro for accelerator studies and technology development to demonstrate the feasibility of an x-ray user facility. This paper presents an overview of the project and the key components of the facility.

 
TUP010 Test Results of Components for CW and Near-CW Operation of a Superconducting Linac HOM, linac, SRF, cathode 413
 
  • J.K. Sekutowicz, M. Ebert, F. Mittag
    DESY, Hamburg
  • P. Kneisel
    JLAB, Newport News, Virginia
  • R. Nietubyc
    The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
 
 

The European XFEL will use superconducting TESLA cavities operating with 650 μs long bunch trains. With 220 ns bunch spacing and 10 Hz RF-pulse repetition rate up to 27000 high quality bunches/s will be delivered to insertion devices generating unprecedented high average brilliance photon beams at very short wavelength. While many experiments can take advantage of full bunch trains, others prefer an increased several μ-seconds intra pulse distance between bunches, or short bursts with kHz repetition rate. With the nominal RF-pulse structure these features will lead to a substantially reduced number of bunches per second and therefore to significantly lower average brilliance. We discuss here an R&D program aiming for a far future upgrade of the European XFEL; operation in the cw and/or near-cw mode. The program profits from the continuous improvement in performance of TESLA cavities, which allows for longer RF-pulses in comparison with the current design. We present test results of a SRF electron injector and a new RF-power source, and some modification of the HOM damping scheme, which will avoid the necessity of re-assembly of the XFEL accelerator for the upgraded operations.

 
TUP013 Commissioning and Early Operating Experience of the FLASH Third Harmonic RF System HOM, FEL, cryomodule, superconducting-cavity 422
 
  • E.R. Harms, H.T. Edwards
    Fermilab, Batavia
  • M. Hüning, E. Vogel
    DESY, Hamburg
 
 

A Third Hamonic/3.9 GHz superconducting RF module was recently installed in the FLASH facility at DESY. Ultra short bunches with high peak current are required to efficiently create high brilliance coherent light and these can be produced by means of a 2-stage transverse magnetic chicane bunch compression scheme coupled with off-crest acceleration. The long bunch tails and reduced peak current which result from the nonlinearities of the RF since wave can be eliminated by the addition of a 3rd harmonic RF system. Such a system can also allow for the creation of uniform intensity bunches of adjustable length necessary for seeded operation. We present here a summary of commissioning and early operating experience of the newly-installed device.

 
TUP014 Construction of Injector System for SPring-8 X-FEL gun, emittance, klystron, controls 425
 
  • H. Hanaki, T. Asaka, H. Ego, H. Kimura, T. Kobayashi, S. Suzuki, M. Yamaga
    JASRI/SPring-8, Hyogo-ken
  • T. Fukui, T. Inagaki, N. Kumagai, Y. Otake, T. Shintake, K. Togawa
    RIKEN/SPring-8, Hyogo
 
 

The injector of the 8 GeV linac generates an electron beam of 1 nC, accelerates it up to 30 MeV, and compresses its bunch length down to 20 ps. Even slight RF instability in its multi-stage bunching section fluctuates the bunch width and the peak current of an electron beam and it accordingly results in unstable laser oscillation in the undulator section. The acceptable instabilities of the RF fields in the cavities, which permit 10% rms variation of the peak beam current, are only about 0.01% rms in amplitude and 120 fs rms in phase according to beam simulation. The long-term RF variations can be compensated by feedback control of the RF amplitude and phase, the short-term or pulse-to-pulse variations, however, have to be reduced as much as possible by improving RF equipment such as amplifiers. Thus we have carefully designed and manufactured the RF cavities, amplifiers and control systems, giving the highest priority to the stabilization of the short-term variations. Components of the injector will be completed by the end of the May 2010, and the injector will be perfected in the summer 2010. We will present the performance of the completed devices in the conference.

 
TUP017 The Resonant Method of Stabilization for Plane of Deflection in the Disk Loaded Deflecting Structures coupling, polarization, controls, linac 434
 
  • V.V. Paramonov, L.V. Kravchuk
    RAS/INR, Moscow
 
 

The hybrid HE11 mode in the cylindrical disk loaded deflectors is twice degenerated. To ensure operational performance and stabilize the position for the plane of deflection, the dispersion curve for modes with perpendicular field polarization must be shifted in frequency with respect to the curve for modes with operating polarization. A lot of decisions, based on the deterioration of the axial symmetry of the structure, are known for this purpose. The resonant method of stabilization is proposed. Resonant elements ' slots, coupled only with modes of perpendicular polarization, are placed in the disks. Two created branches of dispersion curve for composed slot - structure modes are generated and placed symmetrically with respect to the non perturbed dispersion curve for operating modes. In the plane stabilization it provides qualitative advantage with respect a simple frequency shift, because cancels, in the first order, the influence of modes with perpendicular field polarization on the plane of deflection. The criteria for the slots definition are presented. The example of application for the traveling wave S-band deflector is described as well.

 
TUP019 Proton Linac for ADS Application in China linac, rfq, proton, ECR 437
 
  • S. Fu, S.X. Fang, J.Q. Wang
    IHEP Beijing, Beijing
  • X. Guan
    CIAE, Beijing
 
 

In the next two decades, China will be in period of fast development of nuclear power to meet the energy demands of the rapid economy growth and to cut down the CO2 release. Accelerator Driven System is recognized as the best option for nuclear radioactive waste transmutation. ADS long-term development roadmap has been proposed. Based on the ADS basic study in the last decade, a samll-scale ADS facility is going to be built to do experimental research on ADS system. In this paper, we will first review the previous R&D activity on ADS linac research in China, and then introduce the design of the linac in the small-scale ADS facility.

 
TUP020 Accelerator Reference Design for the MYRRHA European ADS Demonstrator linac, proton, target, cryomodule 440
 
  • J.-L. Biarrotte
    IPN, Orsay
  • H. Klein
    IAP, Frankfurt am Main
  • A.C. Mueller
    IN2P3, Paris
  • P. Pierini
    INFN/LASA, Segrate (MI)
  • D. Vandeplassche
    SCK-CEN, Mol
 
 

The goal of the MYRRHA project is to demonstrate the technical feasibility of transmutation in an Accelerator Driven System (ADS) by building a new flexible irradiation complex in Mol (Belgium). The MYRRHA facility requires a 600 MeV accelerator delivering a maximum proton flux of 4 mA CW operation. Such a machine belongs to the category of the high-power proton accelerators, with an additional requirement for exceptional reliability: because of the induced thermal stress to the subcritical core, the number of unwanted beam interruptions should be minimized down to the level of about 10 per 3-month operation cycle, a specification that is far above usual proton accelerators performance. This paper describes the reference solution adopted for such a machine, based on a so-called 'fault-tolerant' linear superconducting accelerator, and presents the status of the associated R&D.

 
TUP023 CH-Cavity Development for the 17 MeV EUROTRANS Injector DTL, linac, proton, simulation 446
 
  • F.D. Dziuba, M. Busch, H. Klein, H. Podlech, U. Ratzinger, C. Zhang
    IAP, Frankfurt am Main
 
 

Recent international cw operated high-current applications with ambitious requirements regarding beam power and quality ask for new linear accelerator developments. In this context the CH-structure (Crossbar-H-mode) has been developed at the Institute for Applied Physics (IAP) of Frankfurt University. It is a multi-cell drift tube cavity for the low and medium energy range operated in the H21-mode and can be used for superconducting as well as for room temperature applications. Because of the large energy gain per cavity, which leads to high real estate gradients, the CH-cavity is an excellent candidate for the efficient acceleration in high power proton and ion accelerators with fixed velocity profiles. One possible application for this kind of cavity is the EUROpean research programme for the TRANSmutation (EUROTRANS) of high level nuclear waste in an accelerator driven system (ADS), which requires an efficient high-current cw-linac (600 MeV, 4 mA, protons, 352 MHz). The paper describes the status of the CH-cavity development and the actual beam dynamics results for the reference design of the 17 MeV EUROTRANS injector.

 
TUP029 Continued Monitoring of the Conditioning of the Fermilab Linac 805 MHz Cavities linac, booster, site, beam-losses 464
 
  • E.S.M. McCrory, F.G. Garcia, T.K. Kroc, A. Moretti, M. Popovic
    Fermilab, Batavia
 
 

We have been collecting data on the conditioning of the high-gradient accelerating cavities in the Fermilab 400 MeV H-Minus Linac for over 16 years [1]. This linac was upgraded in 1989 from a 201 MHz Alverez structure to include 805 MHz side-coupled cavities. Automated measurements of the sparking rate have been recorded since 1994 and are reported here. The sparking rate has declined since the beginning, but there are indications that this rate may have leveled off now. The X-rays emitted by the cavities are continuing to decrease.


[1] Kroc, et al., Proceedings of LINAC96, pp 338-340

 
TUP035 Design Study of C6+ Hybrid Single Cavity Linac for Cancer Therapy linac, rfq, simulation, ion 476
 
  • L. Lu, T. Hattori, N. Hayashizaki
    RLNR, Tokyo
 
 

A new type Linac, HSC (hybrid single cavity) linac for cancer therapy, which configuration combines RFQ (Radio Frequency Quadrupole) accelerating structure and DT (Drift Tube) accelerating structure is being finished designs and simulations now. This HSC linac design had adopted advanced power-efficiency-conformation, IH (Interdigital H) structure, which acceleration efficiency is extremely high in the low-middle energy region, and had also adopted most advanced computer simulation technology to evaluate cavity electromagnetic distribution. The study purposes of this HSC linac focus to design of injector linac for synchrotron of cancer radiotherapy facilities. Here, this HSC linac has an amazing space effect because of compact size by coupled complex acceleration electrode and integrated the peripheral device which is made operation easy to handle. The size of the HSC linac is very compact and is also easy to be adopted for cancer therapy in normal hospital.

 
TUP042 Progress in the Fabrication of the RFQ Accelerator for the CERN Linac4 rfq, linac, vacuum, quadrupole 497
 
  • C. Rossi, P. Bourquin, J.-B. Lallement, A.M. Lombardi, S.J. Mathot, D. Pugnat, M.A. Timmins, G. Vandoni, M. Vretenar
    CERN, Geneva
  • M. Desmons, A. France, Y. Le Noa, J. Novo, O. Piquet
    CEA, Gif-sur-Yvette
 
 

The construction of Linac4, the new 160 MeV CERN H- injector, has started with the goal of improving the LHC injection chain from 2015 with a new higher energy linac. The low energy front end of Linac4 is based on a 352 MHz, 3-m long Radiofrequency Quadrupole (RFQ) accelerator. The RFQ accelerates the 70 mA, 45 keV H- beam from the RF source to the energy of 3 MeV. The fabrication of the RFQ has started at CERN in 2009 and is presently in progress, aiming at the completion of the full structure by early 2011. The RFQ consists of three modules, one meter each; the fabrication alternates machining phases and stress relief cycles, for copper stabilization. Two brazing steps are required: one to assemble the four parts composing a module and a second one to install the stainless steel flanges. In order to monitor that the tight mechanical and alignment budget is not exceeded, metrology measurements at the CERN workshop and RF bead-pull measurements are performed during the fabrication process. In this paper we report results obtained during the machining and the assembly of the first two modules of the Linac4 RFQ and data produced by RF measurements performed during their fabrication.

 
TUP046 Development of the 3MeV RFQ for the Compact Pulsed Hadron Source at Tsinghua University rfq, DTL, vacuum, hadron 509
 
  • Q.Z. Xing, Y.J. Bai, J.C. Cai, X. Guan, X.W. Wang, J. Wei, Z.F. Xiong, H.Y. Zhang
    TUB, Beijing
  • J.H. Billen, L.M. Young
    LANL, Los Alamos, New Mexico
  • W.Q. Guan, Y. He, J. Li
    NUCTECH, Beijing
  • J. Stovall
    CERN, Geneva
 
 

We present, in this paper, the physics and mechanical design of a Radio Frequency Quadrupole (RFQ) accelerator for the Compact Pulsed Hadron Source (CPHS) at Tsinghua University. The 3-meter-long RFQ will accelerate protons from 50 keV to 3 MeV at an RF frequency of 325 MHz. In the physics design we have programmed the inter-vane voltage as a function of beam velocity, to optimize the performance of the RFQ, by tailoring the cavity cross section and vane-tip geometry as a function of longitudinal position while limiting the peak surface electric field to 1.8 Kilpatrick. There will be no Medium-Energy-Beam-Transport (MEBT) following the RFQ. The focusing at the high energy end of the RFQ and at the entrance of the DTL have been tailored to provide continuous restoring forces independent of the beam current. In simulations of the proton beam in the RFQ, using the code PARMTEQM, we observe transmission exceeding 97%. The RFQ is mechanically separated into three sections to facilitate machining and brazing. We have machined a test section and the final RFQ accelerator is now under construction. We will describe the status of the RFQ system in this paper.


* K. R. Crandall et al., RFQ Design Codes, LA-UR-96-1836.

 
TUP049 Vane Machining by the Ball-end-mill for the New RFQ in the J-PARC Linac rfq, linac, factory, gun 518
 
  • T. Morishita, K. Hasegawa, Y. Kondo
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • H. Baba, Y. Hori, H. Kawamata, H. Matsumoto, F. Naito, Y. Saito, M. Yoshioka
    KEK, Ibaraki
 
 

The J-PARC RFQ (length 3.1m, 4-vane type, 324 MHz) accelerates a negative hydrogen beam from 0.05MeV to 3MeV toward the following DTL. We started the preparation of a new RFQ as a backup machine. The new cavity is divided by three unit tanks in the longitudinal direction. The unit tank consists of two major vanes and two minor vanes. A numerical controlled machining with a conventional ball-end-mill has been chosen for the vane modulation cutting instead of the wheel shape cutter. In this presentation we will report the machining procedure, the results of the vane machining, RF properties, and some topics during the fabrication.

 
TUP050 Vacuum Brazing of the New RFQ for the J-PARC Linac vacuum, rfq, linac, controls 521
 
  • T. Morishita, K. Hasegawa, Y. Kondo
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • H. Baba, Y. Hori, H. Kawamata, H. Matsumoto, F. Naito, Y. Saito, M. Yoshioka
    KEK, Ibaraki
 
 

The J-PARC RFQ (length 3.1m, 4-vane type, 324 MHz) accelerates a negative hydrogen beam from 0.05MeV to 3MeV toward the following DTL. We started the preparation of a new RFQ as a backup machine. The new cavity is divided by three unit tanks in the longitudinal direction. The unit tank consists of two major vanes and two minor vanes. A one-step vacuum brazing of a unit tank has been chosen to unite these four vanes together with the flanges and ports. In this presentation we will report the results of the vacuum brazing with the dimension accuracy and an RF property.

 
TUP052 Preliminary Concept for the Project X CW Radio-frequency Quadrupole (RFQ) rfq, vacuum, quadrupole, controls 524
 
  • S.P. Virostek, M.D. Hoff, D. Li, J.W. Staples
    LBNL, Berkeley, California
 
 

Project X is a proposed multi-MW proton facility at Fermi National Accelerator Laboratory. It is the key element for future accelerator complex development intended to support world-leading High Energy Physics (HEP) programs. The Project X front-end would consist of H- ion source(s), a low-energy beam transport (LEBT), radio-frequency quadrupole (RFQ) accelerator(s), and a medium-energy beam transport (MEBT). To support current and future HEP experiments at Fermilab, a CW RFQ is required. One of the chosen RFQ designs has a resonant frequency at 325 MHz. The RFQ provides bunching of the 10 mA H- beam with acceleration up to 2.5 MeV and wall power losses of less than 250 kW. LBNL is currently developing the early designs for various components in the Project X front-end. The RFQ design concept and the preliminary RF and thermal analyses are presented here.

 
TUP054 Latest Commisioning Results of the Siemens Particle Therapy RFQ rfq, ion, linac, synchrotron 530
 
  • S. Emhofer, O. Chubarov, I. Hollenborg, C.M. Kleffner, V.L. Lazarev, M.T. Maier, H. Rohdjess, B. Schlitt, T. Sieber, B. Steiner, P. Urschütz
    Siemens Med, Erlangen
  • H.K. Andersen, M. Budde, F. Bødker, J.S. Gretlund, H.B. Jeppesen, L. Kruse, C.V. Nielsen, C.G. Pedersen, Ka.T. Therkildsen, S.V. Weber
    Siemens DK, Jyllinge
 
 

Siemens is currently preparing, installing and commissioning three IONTRIS particle therapy accelerator systems - two in Germany, in Marburg and Kiel, and one in Shanghai, China. Siemens IONTRIS is based on a synchrotron to accelerate protons and carbon ions for clinical applications up to 250 MeV resp. 430 MeV/u. The injector part consists of an RFQ to accelerate protons and light ions up to 400 keV/u followed by an IH-cavity, wherein the particles achieve 7 MeV/u. The results of the commissioning of the RFQ in the test facility in Denmark will be presented.


*Particle Therapy is a work in progress and requires country-specific regulatory approval prior to clinical use.

 
TUP055 3D Aspects of the IFMIF-EVEDA RFQ: Design and Optimization of the Vacuum Grids, of the Slug Tuners and of the End Cell rfq, vacuum, simulation, insertion 533
 
  • A. Palmieri, F. Grespan, A. Pisent
    INFN/LNL, Legnaro (PD)
  • F. Scantamburlo
    INFN- Sez. di Padova, Padova
 
 

In order to attain the stringent goals that assure the required performances of the IFMIF-EVEDA RFQ in terms of field uniformity, Q-value and RF-induced heat removal capability, the study of the 3D details of the cavity is particularly important. In this paper the main issues regarding the design of the slug tuners, cavity ends and vacuum grids are addressed, as well as the related optimization procedure.

 
TUP057 Completion of the Fabrication of TRASCO RFQ dipole, rfq, vacuum, quadrupole 536
 
  • E. Fagotti, M. Comunian, F. Grespan, A. Palmieri, A. Pisent, C. Roncolato
    INFN/LNL, Legnaro (PD)
 
 

The TRASCO RFQ will accelerate the 40 mA cw proton beam from the ion source to the energy of 5 MeV, for the production of intense neutron fluxes for interdisciplinary applications. The RFQ is composed of six modules of 1.2 m each, assembled by means of ultra high vacuum flanges. The structure is made of OFE copper and is fully brazed. RFQ modules were manufactured in CINEL Scientific Instruments S.r.l. while chemical treatments and brazing were done at CERN. This paper covers the brazing results of the last four modules and low power tests performed for preparation to the high power test of the first electromagnetic segment.

 
TUP058 3D Thermo Mechanical Study on IFMIF-EVEDA RFQ rfq, simulation, vacuum, resonance 539
 
  • F. Scantamburlo, A. Pepato
    INFN- Sez. di Padova, Padova
  • M. Comunian, E. Fagotti, F. Grespan, A. Palmieri, A. Pisent
    INFN/LNL, Legnaro (PD)
 
 

In the framework of the IFMIF/EVEDA project, the RFQ is a 9.8 m long cavity, with very challenging mechanicals specifications. In the base line design, the accelerator tank is composed of 18 modules that are flanged together. An RFQ prototype, composed of 2 modules with a reduced length, aimed at testing all the mechanical construction procedure is under construction. In this paper, the thermo-mechanical study by means of 2D thermo structural and 3D fluid-thermal-structural simulations will be described. The measurements made with a cooling water circuit on a part of the RFQ prototype and the comparison with fluid thermal simulation will be reported.

 
TUP060 Possibility of Thermal Instability for 4-vane RFQ Operation with High Heat Loading rfq, linac, coupling, controls 545
 
  • V.V. Paramonov
    RAS/INR, Moscow
 
 

Due to dispersion properties 4-vane RFQ cavity without resonant coupling is a thermally unstable structure. With deterioration of balance for local detuning there is a possibility for runaway in the field distribution and related thermal effects. It can results, in principle, in irreversible plastic deformations and cavity frequency shift. Both the increment and the threshold of instability are proportional to the average dissipated RF power. This possibility is more probable for long RFQ cavities. Also particularities for the cavity ends design are important. Some general features of this effect are discussed qualitatively and illustrated with simulations.

 
TUP064 The Optimization Design and Tolerance Analysis of DTL in SSC-INAC DTL, emittance, quadrupole, simulation 557
 
  • Z.J. Wang, Y. He, W. Wu, C. Xiao, Y.Q. Yang
    IMP, Lanzhou
 
 

The separated function DTL in SSC(Separated Sector Cyclotron)-linac is being designed. According to the design requirements, 238U34+ ions are accelerated from 0.143MeV/u to 0.976MeV/u throught the DTL. The method coupling DAKOTA(Design Analysis Kit for Optimization and Terascale Application) and beam simulation code BEAMPATH is used to analyze tolerance of the structure. The tolerance of beam parameters to various type of random errors and misalignment are studied with Monte Carlo simulation,so as to de ne the engineering tolerance and alignment. In this paper, the beam dynamics simulation and the tolerance analysis of the SSC-linac are presented.

 
TUP065 Concept Design of CW SC Proton Linac Based on Spoke Cavity for China ADS linac, proton, emittance, simulation 1
 
  • Z. Li
    Southwest University of Science and Technology, Mianyang, Sichuan
 
 

A system ADS study program has been proposed and organized by Chinese Academy of Sciences. As part of the study program, concept design of a 10mA 1.5GeV Continue Wave (CW) superconducting proton linac has been started in the Institute of High Energy Physics (IHEP). In this paper the design of the 325MHz part of this linac, which is composed of a room temperature Radio Frequency Quadrupole (RFQ), eight 4-cell room temperature Cross bar H-type (CH) cavities and three kinds of spoke cavities with total number of 78, is presented. The main parameters and detailed beam dynamic simulation results of the CH and spoke section are introduced.

 
TUP066 Production Design of the Drift Tube Linac for the CERN Linac4 DTL, linac, vacuum, focusing 560
 
  • S. Ramberger, P. Bourquin, Y. Cuvet, A. Dallocchio, G. De Michele, F. Gerigk, J.-M. Giguet, J.-B. Lallement, A.M. Lombardi, E. Sargsyan, M. Vretenar
    CERN, Geneva
 
 

The design of the Drift Tube Linac (DTL) for the new linear accelerator Linac4 at CERN has been made ready for production: H–ion beams of up to 40 mA average pulse current are to be accelerated from 3 to 50 MeV by three RF tanks operating at 352.2 MHz and at duty cycles of up to 10%. In order to provide a margin for longitudinal matching from the chopper line, the longitudinal acceptance has been increased. The synchronous phase starts at -35° in tank1 and ramps linearly to -24° over the tank while it went from -30° to -20° in the previous design. The accelerating gradient has been lowered to 3.1 MV/m in Tank1 and increased to 3.3 MV/m in Tank2 and Tank3 for a better distribution of RF power between tanks that is compatible with a mechanical design. To make the transverse acceptance less sensitive to alignment and gradient errors, the focusing scheme has been changed to FFDD over all 3 tanks. Design features that were demonstrated in earlier reports have been improved for series production. Results of high power RF tests of the DTL prototype equipped with PMQs are reported that test the voltage holding in the first gaps in presence of magnetic fields.

 
TUP070 RF-design and Construction of New Linac Injector for the RIKEN RI-Beam Factory DTL, rfq, linac, impedance 572
 
  • K. Yamada, S. Arai, Y. Chiba, H. Fujisawa, E. Ikezawa, O. Kamigaito, M. Kase, N. Sakamoto, K. Suda, Y. Watanabe
    RIKEN Nishina Center, Wako
  • Y. Touchi
    SHI, Tokyo
 
 

A new linac injector, which will be exclusively used for the RIKEN RI-Beam Factory, has been constructed to increase the beam intensity of very heavy ions such as xenon and uranium. The injector system consists of a superconducting ECR ion source, RFQ linac, three DTLs, and beam transport system including strong quarupole magnets and beam bunchers. Two DTL resonators were newly designed while existing devices including the RFQ* were modified to the other resonators. Direct coupling scheme was adopted for the rf-sytems of the DTLs, where the design study was successfully perfomed by using the MWS code. This paper focuses on the design procedure of the DTLs and RFQ as well as the results of their low and high power tests.


*H. Fujisawa, Nucl. Instrum. and Methods A345 (1994) 23-42.

 
TUP071 Research on Drift Tube Linac Model Cavity for CPHS DTL, rfq, proton, linac 575
 
  • S.X. Zheng, X. Guan, J. Wei, H.Y. Zhang
    TUB, Beijing
  • J.H. Billen, L.M. Young
    TechSource, Santa Fe, New Mexico
  • Y. He, J. Li, D.-S. zhang
    NUCTECH, Beijing
  • J.H. Li
    CIAE, Beijing
  • J. Stovall
    CERN, Geneva
  • Y.L. Zhao
    IHEP Beijing, Beijing
 
 

The CPHS project in Tsinghua University plans to construct a 13 MeV linear accelerator to deliver a pulsed proton beam having an average beam current of 2.5 mA. A Drift Tube Linac (DTL), following a Radio Frequency Quadrupole accelerator(RFQ), will accelerate protons from 3 to 13MeV. The accelerating field and phase will be ramped to match the longitudinal restoring forces at the end of the RFQ. Likewise, the transverse focusing forces, provided by permanent-magnet quadrupole lenses (PMQs) will be programmed to match the transverse restoring forces at the end of the RFQ to avoid missmatch and avoid parametric resonances. We will present the main physics design parameters of CPHS DTL and describe the properties of the resonant cavity. We plan to apply electron beam welding technology exclusively in the fabrication of the drift tubes and will present the test results from our engineering prototyping program.

 
TUP072 An Equivalent Circuit for Post Coupler Stabilization in a Drift Tube Linac DTL, linac, coupling, simulation 578
 
  • F. Grespan
    INFN/LNL, Legnaro (PD)
  • G. De Michele, S. Ramberger, M. Vretenar
    CERN, Geneva
 
 

Post Couplers (PC's) are devices used in order to reduce the effect of perturbations on the operating mode of a DTL, using the resonant coupling stabilization method. In this paper an equivalent circuit for a DTL equipped with PC's is presented, together with a 3D simulation analysis, which can explain the post coupler stabilization principle and define a new tuning strategy for DTL cavities. The PC tuning procedure based on the equivalent circuit and on frequency measurements has been tested and validated with measurements on the Linac4 DTL aluminum model.

 
TUP073 Electro-Dynamics Characteristics of RF Wobbler Cell for Heavy Ion Beam ion, simulation, target, heavy-ion 581
 
  • S. Minaev, N.N. Alexeev, A. Golubev, V.A. Koshelev, T. Kulevoy, B.Y. Sharkov, A. Sitnikov
    ITEP, Moscow
 
 

Intense heavy ion beam is very efficient tool to generate high energy density states in macroscopic amounts of matter. As result it enables unique methods to study astrophysical processes in the laboratory under controlled and reproducible conditions. For advanced experiments on high energy density physics the cylindrical target irradiated by hollow cylindrical beam is required. This combination provides extremely high densities and pressures on the axis of imploding cylinder. A new method for RF rotation of the ion beam is applied for required hollow beam formation. The RF system consisting of two four-cell H-mode cavities is under development for this purpose now. The cavities frequency has been chosen 298 MHz, which is sufficient for uniform target illumination at 100 ns pulse duration. The deflecting electrodes shape has been optimized to provide the uniform deflection of all particles in beam's cross-section. The prototype of the deflector cell was constructed. A measured electro-dynamics characteristic is presented. As well frequency corrections methods are considered in this paper.

 
TUP076 Status of Beam Loss Evaluation at J-PARC Linac beam-losses, linac, proton, background 590
 
  • A. Miura, N. Kikuzawa, T. Maruta, K. Yamamoto
    JAEA/J-PARC, Tokai-mura
  • Z. Igarashi, T. Miyao
    KEK, Ibaraki
  • M. Ikegami
    J-PARC, KEK & JAEA, Ibaraki-ken
  • H. Sako
    JAEA, Ibaraki-ken
  • S. Sato
    JAEA/LINAC, Ibaraki-ken
 
 

Since November, 2007, J-PARC Linac has been operated at 7.2kW beam power. During the operation, beam losses possibly caused by the H0 particles generated by the interaction between H- beam and residual gas in the transport line were observed in the SDTL (Separated-type Drift-Tube Linac) section. In the linac operation, Ar-CO2 gas proportional counters are employed for the measurement of beam loss, but they are also sensitive to background noise of X-ray emitted from RF cavities. In this section, protons, secondary hadrons and gamma rays would be mainly generated as a beam loss, but it is not easy to estimate real beam loss using the proportional counter. The plastic scintillation counters with less X-ray sensitivity and 3He proportional counters with high thermal neutron sensitivity will be also employed to measure the beam loss. The combination of these detectors would bring more accurate beam loss measurements with suppression of X-ray noise. A measurement of emission position and angle distributions of protons due to H- beam loss is being planed. This result would lead to clarify the source of beam loss. This paper reports status of beam loss evaluation using these detectors.

 
TUP077 Solenoid-Based Focusing in a Proton Linac focusing, linac, solenoid, cryomodule 593
 
  • I. Terechkine, J. DiMarco, W. Schappert, D.A. Sergatskov, M.A. Tartaglia
    Fermilab, Batavia
 
 

Development of solenoid-based focusing lenses for transport channel of an R&D linac front end at FNAL is in its final stage. Lenses for the room temperature section of the linac are assembled in individual cryovessels and certified using a devoted stand. During this certification process, for each lens, position of its optical axis relative to the cryovessel is found in the warm and cold state. Lenses for the superconducting sections are ready for production, and development of a cryomodule to house multiple superconducting lenses and RF cavities is in progress. Studies were also conducted to measure fringe magnetic field of a lens in a cryomodule, to investigate a laser-based method of alignment, and to evaluate the extent of beam quality degradation due to imperfections in lens construction and alignment. This report presents some results of these studies.

 
TUP079 SS Helium Vessel Development for 1.3 GHz SRF Cavities at Fermilab niobium, simulation, SRF, controls 596
 
  • N. Dhanaraj, S. Barbanotti, J.S. Brandt, H. Carter, M.H. Foley, J. Grimm, T.N. Khabiboulline, R. Wands
    Fermilab, Batavia
 
 

Fermilab is currently focusing its efforts toward the development of Stainless Steel (SS) helium vessels for its 1.3 GHz SRF cavities. The objective is to transition towards the concept of using SS helium vessels to dress the bare SRF cavities, thereby paving way for significant cost reduction and efficient production techniques for future accelerators. The biggest challenge has been to design a reliable interface between the niobium cavity end group and the stainless steel end flange that encloses the helium vessel. Fermilab has been pursuing a brazed joint design to allow this transition. Additional design challenges associated with this transition are ensuring proper cooling of the cavity, compensating for the difference in thermal contraction between the SS helium vessel and niobium cavities, and also modification of the tuning procedure and ensuring the safety and reliability of the blade and piezo tuners. Current efforts on the qualification of the niobium-SS braze joint, finite element simulations of the thermal design aspects, bench testing of actual cavity displacements, and study of the effects on the tuners will be presented.

 
TUP081 Superconducting RF Cryomodule Production and Testing at Fermilab cryomodule, SRF, superconducting-RF, linac 599
 
  • T.T. Arkan, H. Carter, M.S. Champion, E.R. Harms, R.D. Kephart, J.R. Leibfritz
    Fermilab, Batavia
 
 

Fermilab has produced two cryomodules for superconducting RF (SRF) applications to date. The first of these is an ILC prototype containing eight 1.3 GHz Tesla-type cavities and a superconducting quadrupole. This cryomodule is of the 'Type 3+' design developed by the TESLA collaboration. The assembly of this cryomodule was accomplished at Fermilab with much assistance from DESY and INFN-Milano. The cryomodule was tested at Fermilab in the summer of 2010. The second cryomodule produced at Fermilab contains four 3.9 GHz nine-cell cavities. The cavities and cryomodule were designed at Fermilab; the design concepts are quite similar to the 1.3 GHz Type 3+ cryomodule. This cryomodule was shipped to DESY, tested, and is now operating as part of a third-harmonic system in the FLASH facility. Fermilab plans to build five more 1.3 GHz cryomodules over the next several years for a total of six, which will be installed and operated in the New Muon Lab beam test facility at Fermilab.

 
TUP082 Cryomodule Tests of Tesla-like Cavities in S1-Global for ILC cryomodule, coupling, linac, vacuum 602
 
  • E. Kako, H. Hayano, Y. Kojima, T. Matsumoto, H. Nakai, S. Noguchi, N. Ohuchi, M. Satoh, T. Shishido, K. Watanabe, Y. Yamamoto
    KEK, Ibaraki
 
 

Cryomodule tests of four Tesla-like superconducting cavities is under preparation in the S1-Global project at KEK. Assembly of the cryomodule was started in January 2010, and the installtion in the STF tunnel was completed in April. First cool-down tests are scheduled in June. The low rf power tests of the Tesla-like cavities will be carried out in July. The high rf power tests are scheduled between September and December, 2010.

 
TUP091 Energy and Energy Spread Measurements Using the Rutherford Scattering Technique for Tuning the SARAF Superconducting Linac emittance, proton, rfq, diagnostics 620
 
  • J. Rodnizki, A. Perry, L. Weissman
    Soreq NRC, Yavne
 
 

The SARAF accelerator is designed to accelerate both deuteron and proton beams up to 40 MeV. Phase I of SARAF consists of a a 4-rod RFQ (1.5 MeV/u) and a superconducting module housing 6 half-wave resonators and 3 superconducting solenoids (4-5 MeV). The ions energy and energy spread were measured using the Rutherford scattering technique . This technique is used to tune the cavities to the desired amplitude and phase. The downstream HWR is used as a buncher and the beam energy spread as function of the bunching RF voltage is applied to estimate the longitudinal emittance. In this work, we present a longitudinal emittance measurement algorithm, which is based on the bunch energy spread as a function of the buncher's amplitude, similar to the standard algorithm that uses the bunches' temporal spread. The tuning and measured longitudinal parameters are in qualitative agreement with the predicted beam dynamics simulation.

 
TUP094 Development of Cavity BPM for the European XFEL undulator, dipole, resonance, simulation 629
 
  • D. Lipka, D. Nölle, M. Siemens, S. Vilcins
    DESY, Hamburg
 
 

The European XFEL, currently under construction at the DESY site in Hamburg, require high precision orbit control in the long undulator sections and in addition in some other locations of the machine, like bunch compressors, matching sections, or for the intra bunchtrain feedback system. Due to the pulsed operation of the facility the required high precision has to be reached by single bunch measurements. So far only cavity BPMs achieve the required performance and will be used at the European XFEL. We report on the development of two types of cavity BPMs for the intersection of the undulators with 10 mm beam pipe and for sections with a standard beampipe diameter of 40.5 mm. The prototypes for both types show the properties as expected for simulation results. The paper further concentrates on the industrialisation process. It points out some traps and their cures during the production process.

 
TUP095 Standard E-beam Diagnostics for the European XFEL diagnostics, undulator, FEL, electron 632
 
  • D. Nölle
    DESY, Hamburg
 
 

The European XFEL is a 4th generation synchrotron radiation source, under construction in Hamburg. Based on different Free-Electron-Laser and spontaneous sources, driven by a 17.5 GeV superconducting accelerator, this international facility will provide several user stations with photons simultaneously. Due to superconducting technology high average as well as peak brilliance can be delivered. Flexible bunch pattern are possible for optimum tuning to the experiments demands. This paper will present the current status of the electron beam diagnostics. An overview of the entire system will be given, as well as details on the development of the main systems like BPM, charge and transmission diagnostics, beam size and beam loss monitor systems will be presented. Furthermore, results of first measurements with XFEL prototypes in FLASH will be shown.

 
TUP098 Wakefield Monitor Development for CLIC Accelerating Structure wakefield, linac, alignment, damping 641
 
  • F. Peauger, W. Farabolini, P. Girardot
    CEA, Gif-sur-Yvette
  • A. Andersson, G. Riddone, A. Samoshkin, A. Solodko
    CERN, Geneva
  • R.J.M.Y. Ruber
    Uppsala University, Uppsala
  • R. Zennaro
    PSI, Villigen
 
 

To achieve high luminosity in CLIC, the accelerating structures must be aligned to an RMS accuracy of 5 μm with respect to the beam trajectory. Position detectors called Wakefield Monitors (WFM) are integrated to the structure for a beam based alignment. This paper describes the requirements of such monitors. The development plan and basic feature of the WFM as well as the accelerating structure working at 12 GHz and 100 MV/m are shortly described. Then we focus on detailed electromagnetic simulations and design of the WFM itself. In particular, time domain computations are performed and an evaluation of the intrinsic resolution is done for two higher order modes at 17 and 24 GHz. The mechanical design of the accelerating structure with WFM is also presented. Precise machining with a tolerance of 2.5 μm and a surface roughness of 0.025 μm is demonstrated. The fabrication status of three complete accelerating structures with WFM is finally presented for a feasibility demonstration with beam in CTF3 at CERN.

 
TUP103 Profile Monitors for the SwissFEL Injector Test Facility electron, emittance, radiation, target 656
 
  • R. Ischebeck, B. Beutner, G.L. Orlandi, M. Pedrozzi, T. Schietinger, V. Schlott, V.G. Thominet
    PSI, Villigen
 
 

The SwissFEL Injector Test Facility consists of an RF gun, an accelerating section for a final energy of 250 MeV, and two diagnostics sections. Transverse profiles of the electron beam can be recorded at 27 locations by imaging fluorescent crystals that can be inserted into the beam. At 21 of these, the fluorescent screens are complemented by optical transition radiation monitors and wire scanners. Here, we will evaluate the performance of transverse profile monitors experimentally and numerically and compare the measured profiles with a numerical model of the accelerator. Profile monitors are used in conjunction with a slit and a pepper pot to determine the transverse phase space distribution of the bunches. Experimental measurements at the SwissFEL Injector Test Facility will be presented.

 
TUP109 Large Acceptance Linac for Muon Acceleration linac, solenoid, proton, acceleration 665
 
  • H.M. Miyadera, A.J. Jason, S.S. Kurennoy
    LANL, Los Alamos, New Mexico
 
 

Muon accelerators are studied for future neutrino factory and muon colliders (NF/MC). On the other hand, a compact muon accelerator can be applicable to muon radiography which is a promising probe to investigate large objects. We worked on simulation studies on a compact muon linear accelerator. The designed linac has a large energy and a phase acceptance to capture lower energy pion/muon (10 - 100 MeV) than the NF/MC scenario and accelerates them to 200 MeV without any beam cooling. Our current design adopts 805 MHz zero-mode normal-conducting cavities with 35 MV/m peak field*. The superconducting solenoids are used to provide 5-T focusing field on the normal conducting cavities. We developed a Monte Carlo simulations code to optimize linac parameters. Muon energy loss and scattering effects at the aperture windows are included, too. The simulation showed that about 10 % of the pion/muon injected into the linac can be accelerated to 200 MeV. Further acceleration can be done with superconducting linac.


* S. Kurennoy et al., IPAC 2010.

 
TUP110 Mass Production Report of C-Band Choke Mode Accelerating Structure and RF Pulse Compressor resonance, coupling, acceleration, linac 668
 
  • K. Okihira
    MHI, Kobe
 
 

C-band RF pulse compressor is a device that generates high peak RF-power by saving, and compressing the RF-power output from the klystron. XFEL project is scheduled to be installed 64 pulse compressor units, 2009 of December we have completed the fabrication and RF measurement of all units. A high-power examination was conducted in the test stand at RIKEN. The RF output of the pulse compressor is 260 MW in peak value, and the acceleration gradient of the accelerating structure is achieved to be 40 MV/m.It reports on the mass production passage of these 64 C-Band RF pulse compressors and on the installation result of injector section.

 
TUP111 Status of MICE, the International Muon Ionization Cooling Experiment emittance, target, solenoid, collider 671
 
  • M. Popovic
    Fermilab, Batavia
  • L. Coney
    UCR, Riverside, California
  • P.M. Hanlet
    IIT, Chicago, Illinois
  • D.M. Kaplan
    Illinois Institute of Technology, Chicago, Illinois
 
 

Muon ionization cooling provides the only practical solution to prepare high brilliance beams necessary for a neutrino factory or muon colliders. The muon ionization cooling experiment (MICE) is thus a strategic R&D project for neutrino physics. It is under development at the Rutherford Appleton Laboratory (UK). It comprises a dedicated beam line to generate a range of input emittance and momentum, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. A first measurement of emittance is performed in the upstream magnetic spectrometer with a scintillating fiber tracker. A cooling cell will then follow, alternating energy loss in liquid hydrogen and RF acceleration. A second spectrometer identical to the first one and a particle identification system provide a measurement of the outgoing emittance. In the 2010 run, completed in August, the beam and most detectors have been fully commissioned. The time of the first measurement of input beam emittance is closely approaching. The plan of steps of measurements of emittance and emittance reduction (cooling), that will follow in 2011 and later, will be reported.


I submit this as chair of the MICE speakers bureau. If accepted, I will find a member of the collaboration that will register to the conference and present the contribution.

 
WE101 Design of the Project X CW Linac linac, cryomodule, lattice, focusing 674
 
  • N. Solyak
    Fermilab, Batavia
 
 

Project X is a proposed high-intensity H- accelerator complex that could provide beam for a variety of physics projects: neutrino-, kaon- and muon-based precision experiments. Other applications are under investigation. In the current proposal CW 3MW linac would contains few types of superconducting cavities and focising elements to accelerate beam from 2.5 MeV up to 3 GeV. The paper presents the status of the 3GeV x 1mA CW linac, including design and testing of the linac components, beam physics studies and future plans.

 
WE102 The Status of the SARAF Linac Project rfq, proton, cryogenics, emittance 679
 
  • L. Weissman, D. Berkovits, I. Eliyahu, I. Gertz, A. Grin, S. Halfon, G. Lempert, I. Mardor, A. Nagler, A. Perry, J. Rodnizki
    Soreq NRC, Yavne
  • A. Bechtold
    NTG Neue Technologien GmbH & Co KG, Gelnhausen
  • K. Dunkel, M. Pekeler, C. Piel
    RI Research Instruments GmbH, Bergisch Gladbach
 
 

Phase I of the Soreq Applied Research Accelerator Facility, SARAF, has been installed and is currently being commissioned at Soreq NRC [1]. According to the Phase I design, SARAF should yield 2 mA proton and deuteron beams at energies up to 4 and 5 MeV, respectively. The status of the main Phase I components is reported. We further present beam commissioning results, which include acceleration of a 1 mA CW proton beam up to 3 MeV. Further improvements in the facility in order to achieve the desired performance are discussed.

 

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WE202 Upgrade of Pohang Light Source (PLS) Linac for PLS-II* linac, klystron, gun, storage-ring 698
 
  • S.J. Park, W.H. Hwang, H.-G. Kim, J.M. Kim, K.R. Kim, M. Kim, S.H. Kim, S.-C. Kim, E.H. Lee, S.H. Nam, B.R. Park, S.S. Park, Y.J. Park, Y.G. Son
    PAL, Pohang, Kyungbuk
 
 

Since its completion in 1993, the PLS (Pohang Light Source) linear accelerator has been operated as the full energy injector to the PLS storage ring - a 2.5-GeV 3rd generation light source in Korea. After successful services for more than 15 years to the Korean synchrotron radiation users' community, the PLS is now being upgraded to meet ever-increasing user demands for brighter lights. The PLS-II, the major upgrade program to the PLS, is to increase the beam energy to 3 GeV, changing the storage ring lattice to accommodate large number of insertion devices with lower emittance, and to have the top-up injection as the default operating mode. In order to achieve high injection efficiency (> 80%), beam qualities including the energy spread, pulse length, and jitters in bunch arrival times to the storage ring rf bucket have to be reduced. After successful upgrade of the PLS linac one could further exploit its potential by, for example, implementing high-brightness electron source, which would open up new possibilities with the facility

 

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TH101 Raising the Bar on Superconducting Cavity Processing, and Performance laser, accelerating-gradient, SRF, niobium 708
 
  • Z.A. Conway
    CLASSE, Ithaca, New York
 
 

This talk will give an overview of recent results on the highest gradient SRF cavities, including new, improved surface treatments and cavity repair. Significant recent progress has been made in understanding gradient limiting effects, and how to cure them. Many of these results will be reviewed here.

 

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TH102 SRF and Cryomodule R+D for ERL's HOM, SRF, booster, linac 712
 
  • J. Knobloch
    HZB, Berlin
 
 

A review of the SRF and cryomodule R&D for various ERL projects around the world. Many challenging R&D problems will be addressed such as high average current SRF injectors and CW high gradient SRF modules.

 
TH103 Development and Future Prospects of Rf Sources for Linac Applications klystron, linac, vacuum, collider 717
 
  • E. Jensen
    CERN, Geneva
 
 

This talk gives an overview of recent results and future prospects on RF sources for linac applications, including klystrons, magnetrons and modulators.

 
TH104 Power Coupler Developments for High Intensity Linacs linac, cryomodule, proton, SRF 722
 
  • G. Devanz
    CEA, Gif-sur-Yvette
 
 

Recent developments and promising results are showing the feasibility of 1 MW power couplers for superconducting cavities accelerating high intensity proton beam for projects such as SPL, ESS, EURISOL.

 

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TH202 VECC/TRIUMF Injector for the e-Linac Project linac, electron, TRIUMF, gun 727
 
  • V. Naik, A. Bandyopadhyay, A. Chakrabarti, S. Dechoudhury, M. Mondal
    DAE/VECC, Calcutta
  • F. Ames, R.A. Baartman, C.D. Beard, Y.-C. Chao, R.J. Dawson, P. Kolb, S.R. Koscielniak, R.E. Laxdal, M. Marchetto, L. Merminga, A.K. Mitra, T.C. Ries, I. Sekachev, V.A. Verzilov, F. Yan
    TRIUMF, Vancouver
  • D. Longuevergne
    UBC & TRIUMF, Vancouver, British Columbia
 
 

TRIUMF (Canada) and VECC (India) are both planning to use the photo-fission route for producing neutron-rich radioactive ion beams in their respective RIB programmes. With this common goal the two institutes have entered into a collaboration to jointly design and develop a superconducting 1.3GHz 50MeV, 10 mA, CW electron linac which will be used as the fission driver. The first phase of the e-Linac collaboration aims at the development, production and full technical and beam test of a 10MeV injector cryo module (ICM) which forms the front-end of the final linac. The design and technical development of the ICM will be presented.

 
TH301 Beam Dynamics Studies for Multi-GeV Proton and H-minus Linacs linac, proton, simulation, resonance 735
 
  • J.-P. Carneiro
    Fermilab, Batavia
  • B. Mustapha, P.N. Ostroumov
    ANL, Argonne
 
 

Significant advances were demonstrated in the design and computer simulations of multi-GeV proton and H-minus linacs. Several codes were applied for the simulation of 8 GeV linac and resulted to extremely good coincidence of all beam parameters. New procedures such as stripping of H-minus ions due to various mechanisms were implemented into the tracking code. The author of this presentation has several publications in PRSTAB and Nuclear Instruments on various aspects of beam dynamics for 8 GeV linac.

 

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THP004 Layout and Machine Optimisation for the SPL at CERN linac, HOM, klystron, proton 761
 
  • F. Gerigk, S. Atieh, S. Calatroni, O. Capatina, E. Ciapala, M. Eshraqi, L.M.A. Ferreira, R. Garoby, M. Hernandez Flano, W. Höfle, E. Lebbos, A.M. Lombardi, E. Montesinos, Th. Otto, V. Parma, P.A. Posocco, T. Renaglia, M. Schuh, V. Vlachoudis, W. Weingarten, S. Weisz
    CERN, Geneva
  • R. Calaga
    BNL, Upton, Long Island, New York
 
 

During the past 2 years the Superconducting Proton Linac (SPL) study has grown into an international collaboration with the goal of optimising the architecture of a pulsed superconducting (SC) high-power proton linac. This effort includes the study and prototyping of major technical components, such as SC high-gradient cavities, power couplers, the RF distribution system, HOM couplers, cryo-modules, focusing elements, etc. Even though the effort is driven by CERN specific needs, the established design principles are valid for a range of superconducting linac projects. In this paper we report on the latests decisions concerning the machine architecture and on the ongoing R&D effort for technical components.

 
THP008 Cw RF System of the Project-x Accelerator Front End linac, rfq, solenoid, acceleration 773
 
  • T.N. Khabiboulline, S. Barbanotti, I.G. Gonin, N. Solyak, I. Terechkine, V.P. Yakovlev
    Fermilab, Batavia
 
 

Front end of a CW linac of the Project X contains a H- source, an RFQ, a medium energy transport line with the beam chopper, and a SC low-beta linac that accelerates H- from 2.5 MeV to 160 MeV. SC Single ' spoke Resonators (SSR) will be used in the linac, because Fermilab already successfully developed and tested a SSR for beta 0.21. Two manufactured cavities achieve 2-3 times more than design accelerating gradients. One of these cavities completely dressed, e.g. welded to helium vessel with integrated slow and fast tuners, and tested in CW and pulse regimes. Successful tests of beta=0.21 SSR give us a confidence to use this type of cavity for low beta (0.117) and for high- beta (0.4) as well. Both types of these cavities are under development. In present report the basic constrains, parameters, electromagnetic and mechanical design for all the three SSR cavities, and first test results of beta=0.21 SSR are presented.

 
THP009 Critical Dipole Modes in JLAB Upgrade Cavities HOM, damping, cryomodule, dipole 776
 
  • F. Marhauser, J. Henry, H. Wang
    JLAB, Newport News, Virginia
 
 

The 12GeV upgrade of CEBAF is currently in progress. Ten new cryomodules will be installed at completion of the project to increase the energy from 6GeV to 12GeV. Each cryomodule houses eight seven-cell Low Loss type cavities. The damping of HOMs is crucial to prevent from beam break-up (BBU) instabilities at the desired beam currents as experienced with an upgrade demonstration cryomodule which needed to be de-installed recently. Detailed HOM surveys of a complete string of cavities in a cryomodule as well as individual cavities revealed the existence of critical dipole modes below and above beam tube cutoff that needed extensive experimental and numerical analyses. Results and their consequences for the 12 GeV upgrade cryomodules are detailed.

 
THP010 Exploiting New Electrochemical Understanding of Niobium Electropolishing for Improved Performance of SRF Cavities for CEBAF niobium, cathode, controls, impedance 779
 
  • C.E. Reece, H. Tian
    JLAB, Newport News, Virginia
 
 

Recent incorporation of analytic electrochemistry into the development of protocols for electropolishing niobium SRF cavities has yielded new insights for optimizing this process for consistent, high-performance results. Use of reference electrodes in the electrolyte, electrochemical impedance spectroscopy (EIS), rotating disk electrodes (RDE), and controlled sample temperatures has greatly clarified the process dynamics over the empirical understanding developed via years of practice. Minimizing rf losses at high operational gradients is very valuable for CW linacs. Jefferson Lab is applying these new insights to the low-loss 7-cell cavity design developed for the CEBAF 12 GeV Upgrade. Together with controlled cleaning and assembly techniques to guard against field-emission causing particulates, the resulting process is yielding consistent cavity performance that exceeds project requirements. Cavity tests show BCS-limited Q well above 30 MV/m. Detailed process data, interpretation, and resulting rf performance data will be presented.

 
THP011 First Beam Spectra of sc Third Harmonic Cavity at FLASH HOM, simulation, electron, FEL 782
 
  • P. Zhang, R.M. Jones, I.R.R. Shinton
    UMAN, Manchester
  • N. Baboi, B. Lorbeer, P. Zhang
    DESY, Hamburg
  • T. Flisgen, H.-W. Glock, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock
 
 

Third harmonic superconducting cavities have been designed and fabricated by FNAL to minimise the energy spread along bunches in the FLASH facility at DESY. A module, consisting of four nine-cell 3.9 GHz cavities, has been installed in FLASH. The first measurement with beam excitation is presented, and the comparisons to transmission measurement without beam and simulations are made. Higher order modes (HOMs) are able to propagate to adjacent cavities through attached beam tubes. Modes from 1.3 GHz cavities in the module nearby also propagate into this module.


*Work supported by European Commission under the FP7 Research Infrastructures grant agreement No.227579.

 
THP012 Higher Order Modes in Third Harmonic Cavities at FLASH HOM, simulation, dipole, impedance 785
 
  • R.M. Jones, I.R.R. Shinton, P. Zhang
    UMAN, Manchester
  • N. Baboi
    DESY, Hamburg
  • T. Flisgen, H.-W. Glock, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock
 
 

Transverse modes in the 3.9 GHz cavities designed and fabricated by FNAL are reported on. These modes have the potential to cause significant emittance dilution if they not sufficiently suppressed. Recent experiments, both probe-based and beam-excited, have indicated significant discrepancies between modes predicted in stand-alone 9-cell cavities compared to those in 4-cavity modules. We employ a suite of computer codes and circuit models to analyze these modes, coupled through beam tubes whose cut-off is above that of the first dipole band. We also report on preparations to instrument the higher order mode couplers with electronics suitable for diagnosing both the beam and cavity position, based on modes with sufficient R/Q values.

 
THP013 Testing of Niobium Material for the European XFEL Pre-series Production niobium, controls, superconductivity, vacuum 788
 
  • A. Brinkmann, M. Lengkeit, W. Singer, X. Singer
    DESY, Hamburg
 
 

For the XFEL cavity production a rather large quantity of niobium sheets from partially new niobium vendors has to be delivered according to the XFEL Cavity Specification. It is of high importance that the material monitoring of this niobium has to be done within the production process to ensure a high performance of the cavities. The quality assurance program includes electrical measurements, mechanical, structural and chemical material analysis. For the surface investigations two eddy current scanning devices have been fabricated on the basis of our specification and experience. The scanning process and evaluation of test result can now be done in a few minutes per sheet. We describe the material test methods and the scanning machine. Measured results of the pre-series niobium will be compared to older material tests results.

 
THP014 Progress on Diagnostic Tools for Superconducting High-Gradient Cavities SRF, niobium, linac, cryogenics 791
 
  • F. Schlander, S. Aderhold, E. Elsen, D. Reschke
    DESY, Hamburg
 
 

Superconducting cavities have long been used in particle accelerators. The 1.3 GHz cavities developed in the TESLA collaboration will be the basis of the European XFEL and are the cavity of choice for the International Linear Collider (ILC). The fabrication of the cavities has been optimised over the past 20 years and will now be applied in industrial production of the 800 cavities foreseen for the XFEL. The DESY ILC group is developing tools to monitor those aspects of the production that affect the gradient of these cavities. The main obstacle in achieving a high gradient >30 MV/m is the quench induced in surface structures in the niobium. Such features are explored in an optical inspection of the 9-cell cavity structures and supplemented by measurements of the second sound that originates from the phase transition of the liquid helium at the position of the quench. Oscillating Superleak Transducers (OST) are used to record the signal of the second sound. The second sound measurements are thought to replace the time consuming direct temperature measurements on the outer cavity surface with a resistor system. The status of the various tools will be described.

 
THP015 A Review of the 1.3GHz Superconducting 9-Cell Cavity Fabrication for DESY HOM, higher-order-mode, linac, electron 794
 
  • J. Iversen, R. Bandelmann, G. Kreps, W.-D. Möller, D. Proch, J.K. Sekutowicz, W. Singer
    DESY, Hamburg
 
 

Since 1993 DESY ordered 165 1.3GHz 9-cell superconducting cavities. The cavities have been developed for TeV-Energy Superconducting Linear Accelerator (TESLA) and are used in the linac of the Free Electron Laser in Hamburg (FLASH). The fabrication of all cavities was done in 9 production groups at industry. From the beginning the industrialization was carried out in close collaboration between DESY and the industry. From order to order the cavity design was optimized and the fabrication sequences were improved to realize stable and better cavity performance and to safe costs. Now a final cavity design for the European XFEL is defined. We summarize the development phases and design changes up to the final XFEL design. An outlook on the near future production of hundreds of cavities for XFEL based on our experience will be given.

 
THP017 Developing RF Structures Using Atomic Layer Deposition SRF, niobium, impedance, superconducting-RF 797
 
  • J. Norem, M. Kharitonov, J. Klug, M.J. Pellin, Th. Proslier
    ANL, Argonne
  • N. Becker, J. Zasadzinski
    IIT, Chicago, Illinois
  • G. Ciovati
    JLAB, Newport News, Virginia
  • A.V. Gurevich
    NHMFL, Tallahassee, Florida
 
 

An effort, centered at Argonne, has started to explore the use of Atomic Layer Deposition (ALD) to study and improve the performance of superconducting rf (SRF) accelerating structures. This effort has a number of parts: a survey the properties of ALD deposited films, a study of loss mechanisms of SRF structures, and a program of coating single cell cavities, to begin to optimize the performance of complete systems. Early results have included improving the performance of individual structures and, identification of magnetic oxides as a loss mechanism in SRF. We describe the program and summarize recent progress.

 
THP018 Recent Results of 1.3 GHz 9-cell Superconducting Cavities in KEK-STF radiation, HOM, superconducting-cavity, electron 800
 
  • Y. Yamamoto, H. Hayano, E. Kako, S. Noguchi, M. Satoh, T. Shishido, K. Umemori, K. Watanabe
    KEK, Ibaraki
 
 

MHI#10 and #11 cavities are measured in KEK-STF as the s0 plan for ILC. After these vertical tests, they will be sent to J-Lab and tested at least once there. Moreover, two new cavities without HOM coupler are fabricated and measured in STF, which are made by two new vendors (HITACHI and TOSHIBA). As the international collaboration, one cavity from IHEP in Beijing will be sent to KEK, optical inspected, high pressure rinsed and vertical tested. Although MHI#8 cavity for S1-Global reached 38MV/m, it could not achieve ILC specification (35MV/m, 0.8x109) due to the heavy field emission. To overcome this problem, the various tests were done in the stage of the surface treatment. For example, the EP parameters and the rinsing procedure were changed. In this report, the recent results of the vertical tests including the surface treatment in KEK-STF will be presented in detail.

 
THP021 Higher Order Mode Heating Analysis for the ILC Superconducting Linacs* linac, HOM, scattering, coupling 803
 
  • K.L.F. Bane, C. Adolphsen, C.D. Nantista
    SLAC, Menlo Park, California
 
 

The superconducting cavities and interconnects in the 12 km long linacs of the International Linear Collider (ILC) are designed to operate at 2K where cooling costs are very expensive. Thus it is important to ensure that any additional cryogenic heat loads are small in comparison to those from static losses and the fundamental 1.3 GHz accelerator mode. One potential heat source is the higher order modes (HOM) excited by the beam. Such modes will be damped by specially designed HOM couplers that are attached to the cavities (for trapped modes), and by 70K ceramic dampers that are located in each of the eight or nine cavity cryomodules (for propagating modes). Brute force calculations of the higher frequency, non-trapped modes excited in a string of cryomodules is limited by computing capacity. We present, instead, an approach that combines scattering matrix and wakefield calculations to study the effectiveness of the dampers in limiting the heat deposited in the 2K cryogenic system.

 
THP022 Design Optimisation of the EURISOL Driver Low-beta Cavities vacuum, linac, TRIUMF, electron 806
 
  • Y. Ma
    CIAE, Beijing
  • A. Facco, F. Scarpa
    INFN/LNL, Legnaro (PD)
 
 

The low-beta section of the EURISOL driver linac is based on 176 MHz superconducting half-wave resonators (HWR) with beta=0.09 and 0.16. These cavities are an evolution of the 352 MHz ones, previously developed in the same framework, having similar dimensions and components except for their length and rf frequency. They are characterized by a double wall, all niobium structure with light weight, good mechanical stability and a side tuner cooled by thermal conduction. The new 176 MHz Half-wave cavities design includes a removable tuner, which allows to improve tuning range, mechanical stability and accessibility to the cavity interior. A beta=0.13 cavity, which could be suitable for linacs like the SARAF one, was also designed with the same concepts. Design characteristics and expected performance will be presented and discussed.

 
THP023 Developments and Test of a 700 MHz Prototypical Cryomodule for the MYRRHA ADS Proton Linear Accelerator cryomodule, cryogenics, linac, controls 809
 
  • F.B. Bouly, J.-L. Biarrotte, S. Bousson, C. Commeaux, C. Joly, J. Lesrel
    IPN, Orsay
  • A. Bosotti, P.M. Michelato, R. Paparella, P. Pierini, D. Sertore
    INFN/LASA, Segrate (MI)
 
 

Accelerator Driven systems (ADS) are being considered for their potential use in the transmutation of nuclear waste. Because of the induced thermal stress to the subcritical core, the high-power proton LINAC will have to fulfill stringent reliability requirements and to minimize the number of unwanted beam trips per operation cycle. It is forseen to build an ADS demonstrator (MYRRHA) in Mol (Belgium). Such a device will be piloted by a 600 MeV / 4mA superconducting linac. IPN Orsay and INFN Milano are in charge of the realisation and tests of a prototypical cryomodule for the high energy section of the accelerator, equipped with a 5-cell superconducting cavity. Developed at INFN, this RF cryogenic accelerating device is tested for the first time at IPN. We will describe the status of the R&D activities on this device. The first low power tests of the 5-cell superconducting cavity in its prototypical cryomodule will be reviewed. Those tests aim to evaluate the cavity performances after installation in the module (16MV/m in vertical test) but also to measure the tuning systems behaviors in view of reliability considerations for 'fast fault-recovery scenarios'.

 
THP024 Design Sensitivities of the Superconducting Parallel-Bar Cavity luminosity, HOM, superconductivity, higher-order-mode 812
 
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia
 
 

The superconducting parallel-bar cavity has properties that makes it attractive as a deflecting or crabbing rf structure. For example it is under consideration as an rf separator for the Jefferson Lab 12 GeV upgrade and as a crabbing structure for a possible LHC luminosity upgrade. In order to maintain the purity of the deflecting mode and avoid mixing with the near accelerating mode caused by geometrical imperfection, a minimum frequency separation is needed which depends on the expected deviations from perfect symmetry. We have done an extensive analysis of the impact of several geometrical imperfections on the properties of the parallel-bar cavities and the effects on the beam, and present the results in this paper.

 
THP026 Superconducting RF Cavity Production Processing and Testing at Fermilab cryomodule, vacuum, SRF, diagnostics 815
 
  • C.M. Ginsburg, M.S. Champion, J.P. Ozelis, A.M. Rowe
    Fermilab, Batavia
  • M.P. Kelly
    ANL, Argonne
 
 

The superconducting RF (SRF) cavity production program at Fermilab supports 9-cell 1.3 GHz cavity qualification and preparation for assembling cavities into cryomodules, in support of Project X, ILC, or other future projects. Cavity qualification includes cavity inspection, surface processing, clean assembly, and one or more cryogenic qualification tests which typically include performance diagnostics. The overall goals of the program, facilities and accomplishments are described.

 
THP029 Operating Experience with CC2 at Fermilab's SRF Beam Test Facility controls, LLRF, resonance, acceleration 818
 
  • E.R. Harms, J. Branlard, G.I. Cancelo, K. Carlson, B. Chase, E. Cullerton, A. Hocker, P.W. Joireman, T. Kubicki, J.R. Leibfritz, A. Martinez, M.W. McGee, Y.M. Pischalnikov, J. Reid, W. Schappert, K.R. Treptow, V. Tupikov, P. Varghese, T.J. Zmuda
    Fermilab, Batavia
 
 

Capture Cavity II is the first operational component at the SRF Beam Test Facility now under construction at Fermilab. This 9-cell 1.3 GHz cavity, previously operated in another venue on the Fermilab site, was transported to this facility in early 2009. We will summarize its transport and operation in its new (permanent) home compared to previous performance and also present results of studies, particularly Low Level RF, microphonics/vibration, and Lorentz force de-tuning compensation that have been recently carried out with it.

 
THP031 First High Gradient Test Results of a Dressed 325 MHz Superconducting Single Spoke Resonator at Fermilab cryogenics, controls, LLRF, solenoid 821
 
  • R.C. Webber, T.N. Khabiboulline, R.L. Madrak, T.H. Nicol, L. Ristori, W.M. Soyars, R.L. Wagner
    Fermilab, Batavia
 
 

A new superconducting RF cavity test facility has been commissioned at Fermilab in conjunction with first tests of a 325 MHz, β = 0.22 superconducting single-spoke cavity dressed with a helium jacket and prototype tuner. The facility is described and results of full gradient, CW cavity tests with a high Qext drive coupler are reported. Sensitivities to Q disease and externally applied magnetic fields were investigated. Results are compared to bare cavity results obtained prior to hydrogen degassing and welding into the helium jacket.

 
THP032 Status of the EP Simulations and Facilities for the SPL cathode, simulation, controls, niobium 824
 
  • S. Calatroni, L.M.A. Ferreira, M. Leitao Macatrao, A. S. Skala, M. Sosin, Y.L. Withofs
    CERN, Geneva
  • R. De Waele
    KHLim, Diepenbeek
 
 

CERN is assembling a new vertical electropolishing facility in order to process several niobium cavities of beta 1 and beta 0.65 in the context of the HP-SPL R&D programme. Electrochemical simulations are being used in order to define the optimal cathode geometry to process the cavities in a vertical position. Macroscopic properties of fluid dynamics like the Reynolds number and thermodynamics linked to the power dissipated in the process are taken into account to dimension the main system components. All the materials from the different equipments must be compatible with all chemicals within the required working temperature and pressure. To provide safe operating conditions when handling chemicals or processing cavities, specific safety and protection equipment is also foreseen.

 
THP033 Superconducting Sputtered Nb/Cu QWR for the HIE-ISOLDE Project at CERN cathode, plasma, niobium, linac 827
 
  • S. Calatroni, P. Costa Pinto, A. D'Elia, L.M.A. Ferreira, G. Lanza, M. Pasini, M. Scheubel, M. Therasse
    CERN, Geneva
  • R.E. Laxdal, V. Zvyagintsev
    TRIUMF, Vancouver
 
 

For the foreseen intensity and energy upgrade of the ISOLDE complex at CERN (HIE-ISOLDE project) a new superconducting LINAC based on sputtered Nb/Cu Quarter Wave Resonators (QWRs) of two different beta families will be installed in the next three to five years. A prototype cavity of the higher beta family is currently being developed. In this paper we will discuss the latest developments on the sputtering technique for this kind of cavity geometry. First cold RF measurements will be reported.

 
THP034 Baseline Cavity Design for Cornell's Energy Recovery Linac HOM, linac, higher-order-mode, dipole 830
 
  • N.R.A. Valles, M. Liepe
    CLASSE, Ithaca, New York
 
 

This paper discusses the baseline superconducting RF cavity design to be used in Cornell's Energy Recovery Linac, a next generation light source. We discuss the methods used to obtain the design and present the cavity's figures of merit. The baseline cavity design is ready for prototyping, which will begin in the fall of 2010. Finally, we introduce small variations in the center cell design to increase the threshold current through the cavity by increasing the higher order mode relative frequency spread in the main linac, that have the effect of more than doubling the threshold current to 450 mA.

 
THP035 Prototyping Activities of Low-beta SRF Cavity for the PEFP Proton Linac Extension linac, niobium, SRF, electron 833
 
  • H.S. Kim, Y.-S. Cho, H.-J. Kwon
    KAERI, Daejon
 
 

A superconducting RF cavity with a geometrical beta of 0.42 and a resonant frequency of 700 MHz has been under consideration for an extension program of Proton Engineering Frontier Project (PEFP) to accelerate the proton beam above 100 MeV. A five-cell prototype was fabricated and tested to confirm the fabrication procedure and to check the RF and mechanical properties. High RRR niobium sheets (RRR > 250) were used for the cavity material, whereas reactor grade niobium and NbTi were used for the beam pipe region and the flange, respectively. Double-ring stiffening structure was adopted to reduce the Lorentz force detuning effect. For the vertical test of the prototype cavity, a cryostat with operating temperature of 4.2 K was designed and fabricated. The cryostat was thermally insulated with 40 layers of MLI and the vacuum jacket and equipped with temperature monitors and liquid level sensors. The RF system for driving the cavity is based on PLL to track the resonance condition. The status of the prototype development and the vertical test results will be presented in this paper.

 
THP036 Updates on Sc Cavity Inspection niobium, cryogenics, accelerating-gradient, survey 836
 
  • H. Tongu, M. Ichikawa, Y. Iwashita
    Kyoto ICR, Uji, Kyoto
  • H. Hayano, K. Watanabe, Y. Yamamoto
    KEK, Ibaraki
 
 

Optical inspections on superconducting cavities seem to become familiar to those who are involved in the cavity fabrications. Further improvements on the Kyoto Camera have been carried out these years together with further investigation technique developments, such as high density T-map or eddy current scan. Improvements on Kyoto Camera includes change of EL sheets to LEDs, which raised the brightness 10 times and the lifetime very long as known well. The resolution was also increased. The high density T-map will help to locate a hot spot during the vertical tests and the eddy current scan will be useful for screening of bare Nb sheets with possible defects. These progresses will be reported.

 
THP037 High-Gradient Test of a 3 GHz Single-Cell Cavity linac, hadron, ion, RF-structure 839
 
  • S. Verdú-Andrés, U. Amaldi, R. Bonomi, A. Degiovanni, M. Garlasché
    TERA, Novara
  • A. Garonna
    EPFL, Lausanne
  • C. Mellace, P. Pearce
    A.D.A.M. S.A., Geneva
  • S. Verdú-Andrés
    IFIC, Valencia
  • R. Wegner
    CERN, Geneva
 
 

Proton and carbon ion beams present advantageous depth-dose distributions with respect to X-rays. Carbon ions allow a better control of "radioresistant" tumours due to their higher biological response. For deep-seated tumours proton and carbon ion beams of some nA and energies of about 200 MeV and 400 MeV/u respectively are needed. For these applications TERA proposed the "cyclinac": a high-frequency linac which boosts the hadrons accelerated by a cyclotron. The dimensions of the complex can be reduced if higher accelerating gradients are achieved in the linac. To test the maximum achievable fields, a 3 GHz cavity has been built by TERA. The 19 mm-long cell is foreseen to be excited at 200 Hz by 3 us RF pulses and should reach a 40 MV/m accelerating gradient, which corresponds to a peak surface electric field Es of 260 MV/m. In a first high-power test performed at CTF3 the cell was operated at 50 Hz with a maximum peak power of 1 MW. The maximum Es achieved was above 350 MV/m. The breakdown rate at these field values was around 10-1 bpp/m. The maximum value of the modified Poynting vector is close to the best values achieved by high gradient structures at 12 and 30 GHz.

 
THP038 Ultimate-Gradient Srf Test Cavity and Low Loss Tangent Measurements in Ultra Pure Sapphire coupling, vacuum, niobium, collider 842
 
  • P.M. McIntyre, N. Pogue
    Texas A&M University, College Station, Texas
  • C.E. Reece
    JLAB, Newport News, Virginia
 
 

A 1.3 GHz superconducting test cavity is being developed to test wafer samples of advanced SRF materials with surface fields at or beyond the Nb BCS limit. The mushroom-shaped Nb cavity is dielectric-loaded, with a hemisphere of high-purity sapphire located just above a detachable end flange. Wafer samples are mounted on the end flange. The cavity is operated in the TE011 mode, so no currents flow from the end flange to the side walls. Fields are concentrated on the wafer sample so that the peak surface field there is 4 times greater than anywhere else on the cavity walls. The loss tangent of ultrapure sapphire is critical to the performance of the test cavity. A separate first experiment has been conducted in a special 1.8 GHz cavity to measure this loss tangent in L band as a function of temperature for the first time. Results of the measurement and the final design of the ultimate-gradient test cavity will be presented.

 
THP039 Superconducting Coaxial Resonator Development for Ion Linacs at Michigan State University linac, ion, cryomodule, superconductivity 845
 
  • W. Hartung, S. Bricker, C. Compton, K. Elliott, M. Hodek, J.P. Holzbauer, M.J. Johnson, O.K. Kester, F. Marti, S.J. Miller, D. Norton, J. Popielarski, L. Popielarski, J. Wlodarczak, R.C. York
    NSCL, East Lansing, Michigan
  • A. Facco
    INFN/LNL, Legnaro (PD)
  • E.N. Zaplatin
    FZJ, Jülich
 
 

Niobium quarter-wave resonators (QWRs) and half-wave resonators (HWRs) are being developed at Michigan State University for two projects: a 3 MeV per nucleon superconducting linac for re-acceleration of exotic ions (ReA3, under construction, requiring 15 resonators), and a 200 MeV per nucleon driver linac for the Facility for Rare Isotope Beams (FRIB, under design, requiring 344 resonators). The QWRs (80.5 MHz, optimum beta = 0.041 and 0.085) are required for both ReA3 and FRIB. Both include stiffening elements and frictional dampers. Nine beta = 0.041 QWRs have been fabricated; seven of them have been Dewar tested successfully with a helium vessel for use in ReA3. Production and testing of ten beta = 0.085 QWRs is in progress. The HWRs (322 MHz, optimum beta = 0.29 and 0.53, required for FRIB) are designed for mechanical stiffness and low peak surface magnetic field. A prototype beta = 0.53 HWR has been fabricated, and a prototype beta = 0.29 HWR is planned. This paper will cover the RF and mechanical requirements, the resonator and vessel design, and Dewar testing of production resonators.

 
THP041 An Update on the Study of High-Gradient Elliptical SRF Cavities at 805 MHz for Proton and Other Applications SRF, vacuum, electron, superconducting-cavity 851
 
  • T. Tajima, W.B. Haynes, F.L. Krawczyk, M.A. Madrid, R.J. Roybal, E.I. Simakov
    LANL, Los Alamos, New Mexico
  • W.A. Clemens, K. Macha, R. Manus, R.A. Rimmer, L. Turlington
    JLAB, Newport News, Virginia
 
 

An update on the study of 805 MHz elliptical SRF cavities that have been optimized for high gradient will be presented. An optimized cell shape, which is still appropriate for easy high pressure water rinsing, has been designed with the ratios of peak magnetic and electric fields to accelerating gradient being 3.75 mT/(MV/m) and 1.82, respectively. A total of 3 single-cell cavities have been fabricated and tested with various conditions. In addition, a 6-cell cavity design has been completed including multipacting simulations.

 
THP042 Studies on Superconducting Thin Films for SRF Applications* SRF, electron, klystron, cryogenics 854
 
  • T. Tajima, L. Civale, T. Doi, G.V. Eremeev, N.F. Haberkorn, M. Hawley, A. Matsumoto, R.K. Schulze, A.T. Zocco
    LANL, Los Alamos, New Mexico
  • V.A. Dolgashev, J. Guo, D.W. Martin, S.G. Tantawi, C. Yoneda
    SLAC, Menlo Park, California
  • B. Moeckly
    STI, Santa Barbara, California
 
 

In order to overcome the theoretical limit of ~200 mT peak surface magnetic field for niobium SRF cavities, an idea of coating multi-layer thin film superconductors separated with thin dielectric layers has been suggested. We are testing MgB2, NbN and NbC as candidates for the realization of this idea. The results of surface characterization, Auger depth profile, DC magnetization measurements with SQUID, low- and high-field measurements with a TE013-like mode copper cavity coupled with a 11.4 GHz short-pulse Klystron will be presented.

 
THP043 1.3GHz Cavity Development at TRIUMF linac, TRIUMF, ISAC, cryomodule 857
 
  • R.E. Laxdal, C.D. Beard, A. Grassellino, P. Kolb, S.R. Koscielniak, V. Zvyagintsev
    TRIUMF, Vancouver
  • D. Longuevergne
    UBC & TRIUMF, Vancouver, British Columbia
  • R.S. Orr, W. Trischuk
    University of Toronto, Toronto, Ontario
 
 

TRIUMF has embarked on a 1.3GHz development program to support the construction of a 50MeV 10mA e-Linac for the production of radioactive ion beams through photo-fission. Two single cell bulk niobium cavities have been produced in Canadian Industry. A seven-cell cavity in copper is being fabricated both as a manufacturing model and to test higher order mode calculations. Electro-magnetic and mechanical models of a multi-cell cavity are being done to optimize the final design for high intensity acceleration. The 1.3GHz cavity development program will be presented.

 
THP044 RF Cavity Performance in the ISAC-II Superconducting Heavy Ion Linac linac, cryomodule, ISAC, acceleration 860
 
  • D. Longuevergne
    UBC & TRIUMF, Vancouver, British Columbia
  • C.D. Beard, A. Grassellino, P. Kolb, R.E. Laxdal, V. Zvyagintsev
    TRIUMF, Vancouver
 
 

The ISAC-II superconducting linac consists of forty quarter wave bulk niobium cavities. There are eight and twelve 106MHz cavities at beta=5.7% and 7.1% respectively and twenty cavities at 141MHz at beta=11%. The first twenty have been operating since 2006 (Phase I) and the remainder have been installed for first commissioning in April 2010 (Phase II). Cavity performance statistics of the 2006 cavities have been accumulated to look for signs of systematic degradation in performance. These will be presented. In addition single cavity test results and in situ characterization tests of the first operation of the Phase II cavities will be presented.

 
THP051 Retrospective on Fundamental Power Couplers for the Spallation Neutron Source at Oak Ridge vacuum, cryomodule, neutron, superconducting-cavity 866
 
  • M. Stirbet
    JLAB, Newport News, Virginia
 
 

As of September 2009 a sustainable 1 MW in beam power was achieved at Oak Ridge, continuing to make SNS the highest energy-pulsed neutron source available for scientific research worldwide. This paper evaluates the FPCs designed and built at JLAB for the SNS project, emphasizing their performance and related issues addressed during prototyping, qualification on the RF power test stand at room temperature, superconducting cavity commissioning and successful but challenging operation with beam for more than 5 years.


Mircea. Stirbet@jlab.org

 
THP052 RF Power Generation in LINAC4 klystron, linac, DTL, controls 869
 
  • O. Brunner, E. Ciapala, J.N. Schwerg
    CERN, Geneva
 
 

Linac4 is a linear accelerator for negative Hydrogen ions (H-) which will replace the old Linac2 as linear injector for the CERN accelerators. Its higher energy of 160 MeV will give increased beam intensity in the downstream machines. Linac4 is about 100 m long, normal-conducting, and will be housed in a tunnel about 12 m below ground. The Linac4 tunnel will be connected to the existing chain of accelerators and can be extended to the new injection chain. The high RF power for the Linac4 accelerating structures will be generated by thirteen 1.3 MW klystrons, previously used for the CERN LEP accelerator, and six new 2.8 MW klystrons of all operating at a frequency of 352.2 MHz. The integration of the RF power system in the building is presented. The technical specifications and the performance of the various high-power elements are discussed, with emphasis on the required retuning of the LEP klystrons. The power distribution system including the power splitting requirements are also described.

 
THP053 High Power RF for TRIUMF Injector Cryomodule and Elinac linac, klystron, cryomodule, electron 872
 
  • A.K. Mitra, S. Calic, S.R. Koscielniak, R.E. Laxdal
    TRIUMF, Vancouver
 
 

A 500 kW electron linear accelerator is being proposed at TRIUMF for radioactive ion beam production to support existing rare isotope facility. Present design consists of 100 keV thermionic gun, a normal conducting buncher, an injector module and main linac modules. The design energy is 50 MeV with 10 mA beam current. The linac will operate in cw mode using 1.3 GHz superconducting technology. The injector cryomodule (ICM), uses a nine-cell TESLA type cavity operating at 2 degree Kelvin. The front end of the ICM has a room temperature buncher and also has two superconducting capture cavities which are housed in the same cryomodule as the accelerating multi-cell cavity. Solid state amplifiers are proposed to be used for the buncher and the capture cavities. A 30 kW 1.3 GHz IOT, operating at cw will be used to drive the nine-cell cavity of the ICM. The rf power will be divided into two equal parts and fed to two TTF III type couplers. The same couplers are intended to be used for the remaining accelerator cavities of the e-linac. The e-linac is being proposed to be built in stages. High power Klystrons are to be used to provide rf power to the accelerating cavities.

 
THP054 A Diplexer to Operate Two Cavity Eigenmodes in Parallel gun, SRF, coupling, HOM 875
 
  • A. Arnold
    FZD, Dresden
 
 

To fulfil the demand of future high power and high luminosity FEL and Storage Ring sources, an intensive electron beam with short bunch length, small emittance and large bunch charge is required. Laser driven superconducting radio frequency (SRF) photocathode guns in combination with SRF LINACs appear to be the best solution. First long term operation was demonstrated at the FZD*. In difference to the normal conducting guns, the application of static magnetic fields is not possible. Instead, the use of a transverse electric (TE) mode in parallel to the accelerating mode was proposed. Numerical simulations have shown that such RF focusing can be applied to compensate emittance growth**. This contribution will introduce a possibility to use the existing coaxial RF coupler of TESLA like cavities, as RF power input for TE modes in parallel. An additional coupler component outside the module satisfies the job of combining two frequencies from different sources to one load. Thus, it corresponds to the working principle of a high power RF diplexer. Based on the 3 1/2 cell FZD SRF gun, a concrete technical implementation and results of its operation at the cold cavity will be presented.


* J. Teichert et al., AIP Conf. Proc. 1149, 1119 - 1124 (2009).
** K. Flöttmann, D. Janssen, V. Volkov, Phys. Rev. ST Accel. Beams 7, 090702 (2004).

 
THP055 Multipactor Simulations of the SPL Power Coupler multipactoring, electron, simulation, proton 878
 
  • G. Burt, P.K. Ambattu, A.C. Dexter
    Cockcroft Institute, Lancaster University, Lancaster
  • R. Calaga
    BNL, Upton, Long Island, New York
  • E. Montesinos
    CERN, Geneva
 
 

Multipactor is a limiting factor in many RF power couplers. The SPL coupler is proposed to have a conical matching section between the window and the coaxial section however this section must be checked for multipactor. Multipactor simulations of the coupler up to a few MW's of power were performed using a variety of different codes and the results were compared. Simulations were performed in the conical and straight coaxial sections.

 
THP057 A New Fast Tuning System for ATLAS Intensity Upgrade Cryomodule cryomodule, SRF, linac, vacuum 884
 
  • M.P. Kelly, S.M. Gerbick, M. Kedzie, P.N. Ostroumov, S.I. Sharamentov
    ANL, Argonne
 
 

An upgrade project is underway at the ATLAS superconducting RF (SRF) heavy-ion linac at Argonne National Laboratory to dramatically increase the intensity of both stable beams and short-lived isotopes from the CARIBU fission source. The upgrade includes a new normal conducting RFQ injector and an SRF cryomodule consisting of seven high-performance 72.75 MHz quarter-wave cavities optimized for ions with velocity of 0.077c. The module will deliver more than 17.5 MV of accelerating potential over 5 meters and replace three existing split-ring cryomodules. Key to this performance will be a new cavity fast tuning system that replaces the voltage-controlled-reactance (VCX) fast tuner. The recently completed ATLAS upgrade cryomodule installed in June 2009 has a real estate gradient of 14.5 MV over 4.6 meters, the highest for any low-beta cryomodule, however, performance is 40% less than could be achieved without the VCX. As such, the VCX is being replaced with a high-power rf coupler and a fast piezoelectric-based tuner to be used together to control the cavity phase. Cold test results of a prototype power coupler and piezo-tuner are presented here.

 
THP060 X-band Pulse Compression System using One Channel Circular Polarized Traveling Wave Delay Line simulation, linac, coupling, klystron 890
 
  • M. Yoshida, S. Fukuda, Y. Higashi, T. Higo, N.K. Kudo, S. Matsumoto, H. Matsushita
    KEK, Ibaraki
  • S. Kazakov
    Fermilab, Batavia
 
 

The X-band pulse compression system has been developed for the high gradient experiment of the accelerating structure in the new X-band test facility (Nextef). The one channel circular polarized traveling wave delay line was selected to obtain the higher RF compression efficiency under limited delay line length and the easier operation than the cavity chain type. This delay line of the circular waveguide is also frequently used for the C-band feed line from the modulator floor to the accelerator test floor. Thus the delay line is tilted and has the limited length of around 20m. It is designed to obtain the three times compressed power which has the pulse duration of 150 ns. Further we also proceed the upgrade plan using the TE21 mode to double the pulse duration. In this paper, the design overview of this pulse compression system and the RF components including the mode launcher and the TE11-TE21 reflector will be presented.

 
THP062 Upgrade of the 1.3GHz RF System at FLASH gun, klystron, cryogenics, superconducting-cavity 896
 
  • T. Grevsmühl, S. Choroba, F. Eints, T. Frölich, V.V. Katalev, K. Machau, P. Morozov, R. Wagner, V. Zhemanov
    DESY, Hamburg
 
 

The FLASH RF system consists of several RF stations, which provide RF power up to 10MW at 1.3GHz, 1.3ms and 10Hz repetition rate, each, for the superconducting cavities and the RF gun of the FLASH linear accelerator. During the last upgrade of the FLASH facility several modifications have been made also to the RF system. The oldest RF stations were constructed and manufactured by FNAL more than 15 years ago and have been replaced. Since one additional superconducting accelerator module has been added and one superconducting module and the RF gun have been replaced, modification and rearrangement of the RF waveguide distributions were required. An XFEL type waveguide distribution for the new accelerator module ACC7 and a distribution without individual phase shifters for the exchanged module ACC1 have been installed. A new waveguide distribution for the RF gun allows phase tuning by changing the gas pressure in the waveguides. It will also allow supply the RF gun by a 10MW multi beam klystron instead of the still used 5MW single beam klystron at a later point of time.

 
THP065 Magnetrons as SRF Sources feedback, controls, injection, resonance 902
 
  • M. Popovic, A. Moretti
    Fermilab, Batavia
  • A. Dudas, R.P. Johnson, M.L. Neubauer, R. Sah
    Muons, Inc, Batavia
 
 

Magnetrons are the lowest cost microwave source in dollars/kW, and they have the highest efficiency (typically greater than 85%). However, the frequency stability and phase stability of magnetrons are not adequate when used as power sources for accelerators. Novel variable frequency cavity techniques have been developed to phase and frequency lock the magnetrons, allowing their use for either individual cavities, or cavity strings. Ferrite or YIG (Yttrium Iron Garnet) materials are placed in the regions of high magnetic field of radial-vaned, π−mode structures of a selected ordinary magnetron. A variable external magnetic field that is orthogonal to the magnetic RF field of the magnetron surrounds the magnetron to vary the permeability of the ferrite or YIG material. Measurements of a prototype magnetron will be described.

 
THP068 Compact Solid State Direct Drive RF Linac Experimental Program electron, impedance, injection, resonance 905
 
  • O. Heid, T.J.S. Hughes
    Siemens AG, Healthcare Technology and Concepts, Erlangen
 
 

An RF accelerator driver concept is introduced, which integrates a distributed solid-state RF power source with the RF resonator. The resulting structure plays a double role as RF combiner and particle accelerating structure [1]. The key enabling technologies are Silicon Carbide RF transistors and a power combiner concept which includes insulating parallel cavities to ensure consistent RF current injection. An experimental direct drive lamda/4 cavity with a power rating of 500kW at 150MHz has been constructed. The Direct Drive RF power source consists of 64 RF modules constructed from Silicon Carbide vJFETs, radial power combiner and isolation cavity. The initial results from the integration of the direct drive RF source are presented. These results demonstrate experimentally for the first time the validity of the direct drive concept and the key characteristics of such a drive.


[1] O. Heid, T Hughes. "Compact Solid State Direct Drive RF LINAC" presented at IPAC 2010, Kyoto, Japan.

 
THP070 Simulation Study of the RF Chopper rfq, linac, emittance, simulation 911
 
  • Y. Kondo
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • M. Ikegami, F. Naito
    KEK, Ibaraki
  • J. Qiang
    LBNL, Berkeley, California
 
 

For the beam current upgrade of the J-PARC linac, a new RFQ (RFQ III)is developing. The peak beam current of RFQ III is 50mA. To increase the peak current from the existing RFQ (RFQ I), the longitudinal and/or transverse emittances are expected to be increased. However, the increase of the longitudinal emittance will affect the performance of the RF chopper system. In this paper, detailed simulations of the RF chopper system are described and the requirement for the longitudinal emittance of the RFQ is clarified.

 
THP080 Intrabeam Stripping in H- Linacs linac, radiation, focusing, emittance 929
 
  • V.A. Lebedev, J.-F. Ostiguy, N. Solyak
    Fermilab, Batavia
  • A.V. Aleksandrov, A.P. Shishlo
    ORNL, Oak Ridge, Tennessee
 
 

A beam loss in the superconducting part of the SNS linac has been observed during its commissioning and operation. Although this loss does not prevent the SNS high power operation it results in an almost uniform irradiation of linac components and increased radiation levels in the tunnel. A multi-particle tracking could not explain the beam loss and its dependence on the machine parameters. It was recently found that the loss is related to the intrabeam particle collisions resulting in a stripping of one of two H- ions. The paper describes experimental observations and corresponding calculations of the intrabeam stripping.

 
THP081 The Stretched Wire Method: A Comparative Analysis Performed by Means of the Mode Matching Technique impedance, coupling, vacuum, scattering 932
 
  • M. Panniello, V.G. Vaccaro
    Naples University Federico II and INFN, Napoli
  • M.R. Masullo
    INFN-Napoli, Napoli
 
 

The Wire Method for Coupling Impedance evaluations is quite appealing for the possibility to make bench measurements on the Device Under Test (DUT). However, it is not entirely reliable because the stretched wire perturbs the boundary conditions, introducing a TEM wave that has a zero cut off frequency. We expect that, for frequencies smaller than the cutoff one, this behaviour produces an additional power loss which drastically lowers the high Q resonances of DUT. Above cutoff frequency, the impact of the stretched wire is not as dramatic as below cutoff. The Mode Matching Technique will be used to simulate the measurement with the Wire Method. In this way one may get a result which is not affected by the errors intrinsic of experimental measurements. The same method will be used to get, according to its standard definition, the Coupling Impedance of the real structure. The two results will be compared in order to define the frequency ranges in which they agree or disagree. As expected large discrepancies appear below cutoff frequency, while above cutoff, for certain ranges of parameters, an agreement is found.

 
THP082 Beam Dynamics Simulations and Measurements for the PIAVE-ALPI Linac simulation, linac, ion, emittance 935
 
  • M. Comunian, E. Fagotti, F. Grespan, A. Palmieri, A. Pisent, C. Roncolato
    INFN/LNL, Legnaro (PD)
 
 

As far as beam dynamics is concerned, the layout of the PIAVE-ALPI SuperConducting linac, it is injected either by a XTU tandem, up to 14 MV, or by the s-c PIAVE injector, made with 2 SC-RFQ. The linac (at the present 64 cavities for a total voltage up to 48 MV) is build up in two branches connected by an achromatic and isochronous U-bend. The PIAVE-ALPI complex is able to accelerate beams up to A/q = 7. The linac is quite complex due the presence of several accelerating, (SC RFQs and cavities), focusing and transport elements. The linac operation, optimized for the needs of the users, is described. In particular the effects of a flexible use of the cavities on the beam dynamics is addressed. The automatic tuning procedure of the Toutatis-Tracewin programs is used for the simulation, and the comparison with the actual linac performances is reported.

 
THP084 Further Development of the V-Code for Recirculating Linear Accelerator Simulations simulation, recirculation, linac, dipole 938
 
  • S. Franke, W. Ackermann, T. Weiland
    TEMF, TU Darmstadt, Darmstadt
  • P.A. Görgen, C. Klose, M. Platz
    TU Darmstadt, Darmstadt
 
 

The recirculating Superconducting Darmstadt Linear Accelerator S-DALINAC, installed at the institute for nuclear physics (IKP) at the TU Darmstadt, consist of a 10 MeV Injector and a 40 MeV linac. Utilizing two recirculations, the linac could be used up to three times, leading to a maximal energy for nuclear physics experiments of 130 MeV. This recirculating layout makes it pretty complicated to find an accurate setup for the various beam line elements, especially to match the path length of the recirculated beam with the phase of the accelerating fields. Fast online beam dynamics simulations can advantageously assist the operators because they provide a more detailed insight into the actual machine status. In this paper further developments of the moment based simulation tool V-Code enabling it to simulate recirculating machines are presented together with simulation results.

 
THP089 Beam Dynamics Studies of the REX-ISOLDE Linac in Preparation for its Role as Injector for the HIE-ISOLDE SC Linac at CERN simulation, linac, rfq, emittance 950
 
  • M.A. Fraser, R.M. Jones
    UMAN, Manchester
  • M.A. Fraser, M. Pasini, D. Voulot
    CERN, Geneva
 
 

The superconducting High Intensity and Energy (HIE) ISOLDE linac will replace most of the existing accelerating infrastructure of the Radioactive ion beam EXperiment (REX) at CERN, however, the 101.28 MHz RFQ and 5 MV IH cavity will remain in the role of injector for the upgrade, boosting the beam up to an energy of 1.2 MeV/u. We present the results of a beam dynamics investigation of the injector focused most critically on matching the longitudinal beam parameters from the RFQ to the SC machine, which is complicated largely by the IH cavity employing a Combined Zero Degree* (KONUS) beam dynamics design. The longitudinal beam parameters at the RFQ are reconstructed from measurement using the three-gradient method and combined with beam dynamics measurements and simulations of the IH structure to design the matching section for the SC linac.


*Ratzinger, U., "The IH-structure and its capability to accelerate high current beams," Particle Accelerator Conference, 1991

 
THP090 Modeling A Table Top Storage Ring For A Compact Light Source Using Electromagnetic Field Simulation Tools storage-ring, injection, synchrotron, electron 953
 
  • T. Roggen, H. De Gersem, J.P. Locquet, B. Masschaele
    KU Leuven, Kortrijk
  • M. Zhukova
    Tomsk Polytechnic University, Nuclear Physics Institute, Tomsk
 
 

Large synchrotron radiation facilities have become one of the most powerful instruments for research today. All over the world new facilities are being constructed or designed. The biggest disadvantage of a large synchrotron facility is that the scientific experiments, which are often very sensitive and complex, have to be performed in a dedicated place, sometimes far away from the researcher's home laboratory. Promising compact synchrotron radiation sources, that fit in a typical research lab, have been proposed recently. In this paper results are presented of an initial study of a single body magnet, low electron energy storage ring, performed with the Finite Element (FE) and Finite Difference Time-Domain (FDTD) modeling possibilities in the CST Studio Suite 2010 software package. Insights were obtained for the most crucial components: the magnet yoke, the internal RF cavity and the resonance injection component. Finally, the model of the storage ring was verified using the particle tracker solver which tracks the injected electrons along the ring.

 
THP092 Multipacting Simulation and Analysis for the FRIB Superconducting Resonators Using Track3P simulation, niobium, insertion, linac 959
 
  • Z. Li, L. Ge, K. Ko
    SLAC, Menlo Park, California
  • W. Hartung, J.P. Holzbauer, J. Popielarski
    NSCL, East Lansing, Michigan
 
 

In the driver linac of the Facility for Rare Isotope Beams (FRIB), multipacting is an issue of concern for the superconducting resonators, which must accelerate the ion beams from 0.3 MeV per nucleon to 200 MeV per nucleon. While most of the multipacting bands can be conditioned and eliminated with RF, hard multipacting barriers may prevent the resonators from reaching the design voltage. Using the ACE3P code suite, multipacting bands can be computed and analysed with the Track3P module to identify potential problems in the resonator design. This paper will present simulation results for multipacting in half-wave and quarter-wave resonators for the FRIB driver linac and compare the simulations with RF measurements on the resonators.

 
THP096 Investigation of the Effects of Charge Scaling on Emittance Exchange at the Fermilab A0 Photoinjector emittance, quadrupole, space-charge, booster 962
 
  • A.S. Johnson, H.T. Edwards, E.R. Harms, A.H. Lumpkin, J. Ruan, J.K. Santucci, Y.-E. Sun, R. Thurman-Keup
    Fermilab, Batavia
  • P. Piot
    Northern Illinois University, DeKalb, Illinois
 
 

Next generation accelerators, such as high-energy physics colliders and light sources, will be interested in phase space manipulations techniques within two degrees of freedom for enhanced performance. At the Fermilab A0 Photoinjector, a proof-of-principle experiment to demonstrate the exchange of the transverse and longitudinal emittances is ongoing. The emittance exchange beamline consists of a 3.9 GHz normal conducting deflecting mode cavity inserted between two doglegs. Electron bunches of varying charge levels from 250 pC to 1 nC and energy of 14.3 MeV are consistently sent through the exchange beamline. In this paper we will present our latest results on the effects of charge on the emittance exchange process.

 
THP105 Design of a 1 kHz Repetition Rate S-Band Photoinjector gun, emittance, solenoid, cathode 977
 
  • J.H. Han
    Diamond, Oxfordshire
 
 

At many laboratories S-band photoinjectors operate to provide high quality beams; however the repetition rates are limited to about 100 Hz. This limitation mainly occurs due to the guns where a high RF amplitude of about 100 MV/m is required to keep the beam quality from the space charge force. In this paper we design an injector consisting of an S-band gun with improved cooling and S-band acceleration modules for a repetition rate up to 1 kHz. The technical feasibility and beam dynamics optimization are discussed.

 
THP110 Generation of Long Bunch Train using RF Gun gun, linac, laser, beam-loading 992
 
  • A. Deshpande
    Sokendai, Ibaraki
  • S. Araki, M.K. Fukuda, N. Terunuma, J. Urakawa
    KEK, Ibaraki
  • K. Sakaue, M. Washio
    RISE, Tokyo
 
 

At Laser Undulator Compact X-ray Source (LUCX) facility at KEK, we have developed a RF gun with increased mode separation. Using this RF gun we have successfully generated a bunch train of 300 bunches per train with 160 nC total charge and with peak to peak energy difference less than 0.85% at 5.2 MeV. We plan to generate and accelerate 8000 bunches per train with 0.5 nC per bunch. These bunches will then collide in the collision chamber with laser pulses to produce soft x-ray. After successful results from above work, we take next step and are now designing and fabricating a new 3.5 cell RF gun and a high gradient standing wave linac to achieve 50 MeV beam with 8000-bunches per train. This compact source will be used for future research. This paper details achieved results with existing gun for generation of long bunch train and lists out proposed activity.

 
THP112 CW Superconducting RF Photoinjector Development for Energy Recovery Linacs cathode, SRF, niobium, plasma 998
 
  • A. Neumann, W. Anders, M. Dirsat, A. Frahm, A. Jankowiak, T. Kamps, J. Knobloch, O. Kugeler, T. Quast, J. Rudolph, M. Schenk, M. Schuster
    HZB, Berlin
  • P. Kneisel
    JLAB, Newport News, Virginia
  • R. Nietubyc
    The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
  • T. Rao, J. Smedley
    BNL, Upton, Long Island, New York
  • J.K. Sekutowicz
    DESY, Hamburg
  • I. Will
    MBI, Berlin
 
 

ERLs have the powerful potential to provide very high current beams with exceptional and tailored parameters for many applications, from next-generation light sources to electron coolers. However, the demands placed on the electron source are severe. It must operate CW, generating a current of 100 mA or more with a normalized emittance of order 1 μm rad. Beyond these requirements, issues such as dark current and long-term reliability are critical to the success of ERL facilities. As part of the BERLinPro project, Helmholtz Zentrum Berlin (HZB) is developing a CW SRF photoinjector in three stages, the first of which is currently being installed at HZB's HoBiCaT facility. It consists of an SRF-cavity with a Pb cathode and a superconducting solenoid. Subsequent development stages include the integration of a high-quantum-efficiency cathode and RF components for high-current operation. This paper discusses the HZB roadmap towards an ERL-suitable SRF photoinjector, the present status of the facility and first cavity tests.

 
THP120 First Test Result of the IHEP-01 Large Grain 9-Cell Cavity niobium, SRF, HOM, target 1022
 
  • J. Gao, J.P. Dai, Z.D. Guo, M. Hou, Z.Q. Li, L.L. Men, Q.Y. Wang, Q. Xiao, J.Y. Zhai
    IHEP Beijing, Beijing
  • H. Hayano, E. Kako, S. Noguchi, M. Sawabe, T. Shishido, N. Toge, K. Watanabe, Y. Yamamoto
    KEK, Ibaraki
  • T.X. Zhao
    IHEP Beiing, Beijing
 
 

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. As the key component of the 'IHEP 1.3 GHz SRF Accelerating Unit and Horizontal Test Stand Project', a low-loss shape 9-cell cavity using Ningxia large grain niobium (IHEP-01) was fabricated and surface treated (CBP, CP, annealing, pre-tuning) at IHEP. Then the cavity was shipped to KEK STF for ultrasonic cleaning, high pressure rinsing, baking and vertical test. The cavity reached 20 MV/m in the first vertical test on July 1st 2010. The quench location has been found by T-mapping and optical inspection. The strong field emission and equator defects will be removed by further treatment. The fabrication procedure, surface treatment recipes and the first test results are summarized in this paper.

 
THP121 Development of an L-band RF Gun for High-duty-cycle Operation gun, resonance, vacuum, electron 1025
 
  • G. Isoyama, R. Kato, N. Sugimoto
    ISIR, Osaka
  • H. Hayano, H. Sugiyama, T. Takatomi, J. Urakawa
    KEK, Ibaraki
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai
  • M. Kuriki
    HU/AdSM, Higashi-Hiroshima
 
 

We are developing an L-band photocathode RF gun in collaboration with KEK and Hiroshima University. The RF gun will be used not only at Osaka University but also at STF of KEK, so that it can be stably operated at the input RF power of 5 MW with 1 ms duration and a 5 Hz repetition rate, resulting in the average input power of 25 kW. The water-cooling system of the 1.5 cell cavity is designed, which can take the heat with the temperature rise of the cavity body by 5°C at the flow rate of cooling water of 358~723 liter/min. The several parts of the RF cavity are assembled with brazing and the most crucial process is brazing of three main components of the RF cavity into one. The brazing has to be tight and perfect not to allow vacuum leak, while the brazing filler metal must not go out on to the inner surface of the cavity to avoid discharge triggered by the scabrous filler metal on the cavity wall. Test experiments are conducted and a guideline is concluded for such brazing.

 
FR101 Advances in Parallel Electromagnetic Codes for Accelerator Science and Development wakefield, simulation, gun, cryomodule 1028
 
  • K. Ko, A.E. Candel
    SLAC, Menlo Park, California
 
 

SLAC has developed a comprehensive suite of 3D parallel electromagnetic codes based on the finite-element method to solve large-scale computationally challenging problem with high accuracy. The ACE3P (Advanced Computational Electromagnetic 3P) code suite includes the Omega3P eigenmode and S3P S-parameter solvers in the frequency domain for cavity prototyping and optimization, T3P time-domain solver for wakefields and impedances, Track3P particle tracking solver for simulating multipacting and dark current, and Pic3P Particle-in-cell code for RF Gun design. These capabilities with recent advances and the latest applications addressing important RF related accelerator phenomena will be presented.

 

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FR105 Study of Basic Breakdown Phenomena in High Gradient Vacuum Structures accelerating-gradient, vacuum, collider, electron 1043
 
  • V.A. Dolgashev
    SLAC, Menlo Park, California
 
 

We present the results of R&D aimed at exploring the basic physics of RF breakdown phenomena in high vacuum structures. We performed an extensive experimental survey of materials for RF magnetic field induced metal fatigue. To do this, we designed a cavity operating at a TE01m-like mode which focuses RF magnetic field on the flat sample surface. We tested more than 20 samples of materials including single crystal copper, copper alloys, and refractory metals. With these results in hand, we constructed standing wave cavities of different geometries and materials to conduct RF-breakdown experiments. To study a broad range of materials and surfaces, we explored different structure-joining techniques, including those which allow us to avoid high temperature brazing. Using structures of different geometries, we examined the effect of the mixture of surface electric and magnetic fields on breakdown behavior. To study this effect further we designed a structure in which we can adjust the mixture of fields using two independent RF sources.

 

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FR202 Muon Colliders and Neutrino Factories collider, factory, acceleration, electron 1048
 
  • S. Geer
    Fermilab, Batavia
 
 

Over the last decade there has been significant progress in developing the concepts and technologies needed to produce, capture and accelerate O(1021) muons/year. This development prepares the way for a new type of neutrino source (Neutrino Factory) and a new type of very high energy lepton-antilepton collider (Muon Collider). A review is given of the motivation, design and R&D for Neutrino Factories and Muon Colliders.

 

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