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Paper Title Other Keywords Page
MPPP016 Adaptive Feed Forward Beam Loading Compensation Experience at the Spallation Neutron Source Linac SNS, beam-loading, Spallation-Neutron-Source, linac 1467
  • K.-U. Kasemir, M. Champion, M.T. Crofford, H. Ma
    ORNL, Oak Ridge, Tennessee
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

When initial beam studies at the Spallation Neutron Source (SNS) indicated a need for better compensation of the effects of beam loading, a succession of rapid-prototyping and experimentation lead to the development of a simple yet successful adaptive feed forward technique within a few weeks. We describe the process and first results.

MPPT082 The 8 cm Period Electromagnetic Wiggler Magnet with Coils Made from Sheet Copper wiggler, power-supply, electron, undulator 4093
  • G.H. Biallas, S.V. Benson, T. Hiatt, G. Neil, M.D. Snyder
    Jefferson Lab, Newport News, Virginia
  Funding: Work supported by the US DOE Contract #DE-AC05-84ER40150, the Office of Naval Research, the Air Force Research Laboratory, the U.S. Army Night Vision Laboratory and the Commonwealth of Virginia.

An electromagnetic wiggler, now lasing at the Jefferson Lab FEL, has 29 eight cm periods with K variable from 0.6 to1.1 and gap of 2.6 cm. The wiggler was made inexpensively in 11 weeks by an industrial machine shop. The conduction cooled coil design uses copper sheet material cut to forms using water jet cutting. The conductor is cut to serpentine shapes and the cooling plates are cut to ladder shape. The sheets are assembled in stacks insulated with polymer film, also cut with water jet. The coil design extends the serpentine conductor design of the Duke OK4 to more and smaller conductors. The wiggler features graded fields in the two poles at each end and trim coils on these poles to eliminate field errors caused by saturation. An added critical feature is mirror plates at the ends with integral trim coils to eliminate three dimensional end field effects and align the entrance and exit orbit with the axis of the wiggler. Details of construction, measurement methods and excellent wiggler performance are presented.

TPAE016 The Argonne Wakefield Accelerator Facility: Status and Recent Activities electron, gun, laser, cathode 1485
  • M.E. Conde, S.P. Antipov, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, H. Wang, Z.M. Yusof
    ANL, Argonne, Illinois
  Funding: This work is supported by the U.S. Department of Energy, under contract No. W-31-109-ENG-38.

The Argonne Wakefield Accelerator Facility (AWA) is dedicated to the study of electron beam physics and the development of accelerating structures based on electron beam driven wakefields. In order to carry out these studies, the facility employs a photocathode RF gun capable of generating electron beams with high bunch charges (up to 100 nC) and short bunch lengths. This high intensity beam is used to excite wakefields in the structures under investigation. The wakefield structures presently under development are dielectric loaded cylindrical waveguides with operating frequencies of 7.8 or 15.6 GHz. The facility is also used to investigate the generation and propagation of high brightness electron beams. Presently under investigation, is the use of photons with energies lower than the work function of the cathode surface (Schottky-enabled photoemission), aimed at generating electron beams with low thermal emittance. Novel electron beam diagnostics are also developed and tested at the facility. The AWA electron beam is also used in laboratory-based astrophysics experiments; namely, measurements of microwave Cherenkov radiation and fluorescence of air. We report on the current status of the facility and present recent results.

TPPP054 Studies of RF Breakdown of Metals in Dense Gases resonance, collider, hadron, vacuum 3259
  • P.M. Hanlet, M. Alsharo'a, R.P. Johnson, M. Kuchnir, K. Paul
    Muons, Inc, Batavia
  • C.M. Ankenbrandt, A. Moretti, M. Popovic, V. Yarba
    Fermilab, Batavia, Illinois
  • D.M. Kaplan, K. Yonehara
    Illinois Institute of Technology, Chicago, Illinois
  Funding: This work was supported in part by DOE STTR grant DE-FG02-02ER86145.

A study of RF breakdown of metals in gases has begun as part of a program to develop RF cavities filled with dense hydrogen gas to be used for muon ionization cooling. A pressurized 800 MHz test cell has been used at Fermilab to compare the conditioning and breakdown behavior of copper, molybdenum, chromium, and beryllium electrodes as functions of hydrogen and helium gas density. These results are compared to the predicted or known RF breakdown behavior of these metals in vacuum.

TPPT010 HOM Damping of ARES Cavity System for SuperKEKB coupling, dipole, damping, luminosity 1186
  • T. Kageyama, T. Abe, H. Sakai, Y. Takeuchi
    KEK, Ibaraki
  The ARES cavity scheme is a decisive edge for KEKB to stably accelerate high-current electron and positron beams. The RF structure is a coupled-cavity system where a HOM-damped accelerating cavity is coupled with a large cylindrical energy storage cavity via a coupling cavity between. The HOM-damped structure is designed to be smoothly embedded into the whole coupled-cavity scheme without any structural or electromagnetic incompatibility. Currently, the total HOM power dissipated in the RF absorbers per cavity is about 5 kW according to calorimetric measurements in the KEKB LER with a beam current of 1.6 A. On the other hand, for SuperKEKB aiming at luminosity frontiers over 1035 cm-2 s-1, the total HOM power per cavity is estimated about 100 kW for the LER with the design beam current of 9.4 A. In this article, a new HOM-damped structure of the ARES cavity system designed for the SuperKEKB LER is reported together with the recent activities and future plans for upgrading the HOM absorbers.  
TPPT011 R&D Status of C-Band Accelerating Section for SuperKEKB linac, positron, luminosity, coupling 1233
  • T. Kamitani, N. Delerue, M. Ikeda, K. Kakihara, S. Ohsawa, T. Oogoe, T. Sugimura, T. T. Takatomi, S. Yamaguchi, K. Yokoyama
    KEK, Ibaraki
  • Y. Hozumi
    GUAS/AS, Ibaraki
  For future energy upgrade of the KEKB injector linac, C-band accelerating section has been developed. First prototype 1-m long section has been installed in the linac and has achieved the accelerating field gradient of 42 MV/m. Developments of second prototype which has thicker coupler iris and third prototype which has smooth surface of the iris are in progress for less frequent breakdown. This paper reports on the recent R and D status of these C-band accelerating sections.  
TPPT018 Tuning of 20MeV PEFP DTL target, proton, insertion, simulation 1598
  • M.-Y. Park, Y.-S. Cho, H.-S. Kim, H.-J. Kwon, K.T. Seol, Y.G. Song
    KAERI, Daejon
  Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government.

The PEFP (Proton Engineering Frontier Project) 20 MeV DTL have been constructing in KAERI site. The tuning goals for PEFP DTL are achieving the tank frequency as ± 5 kHz of designed resonant frequency and 1% of field profile through a tank. To tune the tank frequency 8 low power slug tuners per tank are fabricated and the tuning range is ±125 kHz per a tuner. Post couplers with tap to stabilize the field against the perturbation also are fabricated and will be installed every 3rd (1st tank) and 2nd (2,3,4th tank) drift tubes. We set up the bead perturbation measurement equipment as measuring the phase shift of a tank using network analyzer and LabView program. We are finalizing the tuning procedures and also the data calculation program. In this presentation we will show the overall features of the PEFP DTL tuning and discuss the measurement results.

TPPT035 High-Power RF Testing of a 352-MHz Fast-Ferrite RF Cavity Tuner at the Advanced Photon Source resonance, coupling, photon, RF-structure 2407
  • D. Horan, E.E. Cherbak
    ANL, Argonne, Illinois
  Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under contract No. W-31-109-ENG-38.

A 352-MHz fast-ferrite rf cavity tuner, manufactured by Advanced Ferrite Technology, was high-power tested on a single-cell copper rf cavity at the Advanced Photon Source. These tests measured the fast-ferrite tuner performance in terms of power handling capability, tuning bandwidth, tuning speed, stability, and rf losses. The test system comprises a single-cell copper rf cavity fitted with two identical coupling loops, one for input rf power and the other for coupling the fast-ferrite tuner to the cavity fields. The fast-ferrite tuner rf circuit consists of a cavity coupling loop, a 6-1/8” EIA coaxial line system with directional couplers, and an adjustable 360° mechanical phase shifter in series with the fast-ferrite tuner. A bipolar DC bias supply, controlled by a low-level rf cavity tuning loop consisting of an rf phase detector and a PID amplifier, is used to provide a variable bias current to the tuner ferrite material to maintain the test cavity at resonance. Losses in the fast-ferrite tuner are calculated from cooling water calorimetry. Test data will be presented.

TPPT039 Installation and Testing for Commissioning of Normal Conducting RF Linac Segment in the SNS linac, SNS, rfq, resonance 2571
  • Y.W. Kang, A.V. Aleksandrov, D.E. Anderson, M.M. Champion, M. Champion, M.T. Crofford, C. Deibele, G.W. Dodson, R.E. Fuja, P.E. Gibson, P.A. Gurd, T.W. Hardek, G.A. Johnson, P. Ladd, H. Ma, M.P. McCarthy, M.F. Piller, J.Y. Tang, A.V. Vassioutchenko, D.C. Williams
    ORNL, Oak Ridge, Tennessee
  • J.A. Billen, J.T. Bradley, D. Rees, W. Roybal, J. Stovall, K.A. Young, L.M. Young
    LANL, Los Alamos, New Mexico
  The Spallation Neutron Source (SNS) linac employs both normal conducting and superconducting linac cavities that will inject a 1.0 GeV proton beam into its accumulator ring. The normal conducting segment of this linac accelerates the beam to 185 MeV and employs one RFQ and six DTL cavities powered by seven 2.5 MW, 402.5 MHz klystrons and four CCL modules powered by four 5.0 MW, 805 MHz klystrons. Installation and RF conditioning of the RF equipment for normal conducting linac segment have been completed at ORNL with the support of LANL experts. After conditioning the accelerating structures, the linac has been successfully commissioned with beam. This paper reviews the experience in installation, RF conditioning, and commissioning of the normal conducting linac accelerating structures and RF subsystems. Checkout and operation of the RF systems and structures including conditioning procedure establishment and test results compared to the RF design specifications will be discussed.

SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

TPPT050 Rod-Loaded and PBG Multi-Beam Klystron Cavities coupling, dipole, lattice, cathode 3094
  • A. Smirnov, D. Yu
    DULY Research Inc., Rancho Palos Verdes, California
  Funding: Work supported by DOE SBIR Grant No. DE-FG02-03ER83845.

Performance of PBG-like structures was studied for multi-defect and single-defect metal cavities. Conceptual designs of a 6-beam, X-band, multi-beam klystron (MBK) demonstrate feasibility of high power generation with efficiency ~63% in a compact structure. Sheet-beam and annular-beam rod-loaded configurations were also investigated.

TPPT054 CW Operation of the TTF-III Input Coupler vacuum, linac, simulation, beam-loading 3292
  • J. Knobloch, W. Anders, M. Martin
    BESSY GmbH, Berlin
  • S. Bauer, M. Pekeler
    ACCEL, Bergisch Gladbach
  • S.A. Belomestnykh
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  • A. Buechner, H. Buettig, F.G. Gabriel
    FZR, Dresden
  • D. Kostin, W.-D. Müller
    DESY, Hamburg
  Many newly proposed light sources, operating in the CW regime, are based on superconducting TESLA technology. Since this was originally developed for pulsed, 1-% duty-factor operation, it is important to determine the limitations of the TESLA cryomodule and its components when operated CW. Among the critical components is the RF input coupler. Two tests have been performed to determine the average power limit of the TTF-III system. First, room temperature tests up to 4 kW were performed at the Forschungszentrum Rossendorf. These permitted the calibration of computer codes developed to calculate the temperature distribution in the coupler. The programs then were used to make predictions for the (normal) cold operation of the coupler. At BESSY, the coupler test stand was assembled inside the HoBiCaT horizontal cryostat test facility to operate the coupler in an environment close to that of a real accelerator. The results of the two tests are presented here.  
TPPT062 High Power Test of the Prototype Cryomodule for ADS Superconducting Linac linac, target, radiation, feedback 3579
  • E. Kako, S. Noguchi, N. Ohuchi, T. Shishido, K. Tsuchiya
    KEK, Ibaraki
  • N. Akaoka, H. Kobayashi, N. Ouchi
    JAERI/LINAC, Ibaraki-ken
  • E. Chishiro, T. Hori, M. Nakata, M. Yamazaki
    JAERI, Ibaraki-ken
  A prototype cryomodule containing two 9-cell superconducting cavities of beta=0.725 and fo=972MHz had been constructed under the collaboration of Japan Atomic Energy Research Institute (JAERI) and High Energy Accelerator Research Organization (KEK) on the development of superconducting LINAC for Accelerator Driven System (ADS). Cool-down tests to 2.0K of the cryomodule and high power tests with a 972MHz pulsed klystron have been successfully carried out. Rf power of 350kW in a pulsed operation of 3msec and 25Hz was transferred to the nine-cell cavity through an input coupler. Accelerating gradients of about 14MV/m higher than the specification (10MV/m) were achieved in both cavities. Design and performance of the prototype cryomodule and the test results with high rf power will be reported.  
TPPT066 Successful Operation of the 500 MHz SRF Module at TLS synchrotron, electron, photon, injection 3706
  • C. Wang, L.-H. Chang, S.-S. Chang, C.-T. Chen, F.-T. Chung, F.-Z. Hsiao, G.-Y. Hsiung, K.-T. Hsu, C.-C. Kuo, H.C. Li, M.-C. Lin, R.J. Lin, Y.K. Lin, G.-H. Luo, M.H. Tsai, J.Y. Yang, T.-T. Yang, M.-S. Yeh
    NSRRC, Hsinchu
  A superconducting radio frequency (SRF) cavity of CESR-III design was installed sucessfully in the electron storage ring at the National Synchrotron Radiation Research Center (NSRRC) in Taiwan. The project goals are to double the photon flux by raising the electron beam current and to increase the beam stability by taking advantage of the well-damped high-order modes of SRF cavity. Nowadays, SRF cavity has become the key technology for new synchrotron light sources under construction or planning worldwide. The first operational experience of the SRF cavity at the NSRRC will be presented.  
TPPT083 RF Conditioning and Testing of Fundamental Power Couplers for SNS Superconducting Cavity Production vacuum, SNS, Spallation-Neutron-Source, instrumentation 4132
  • M. Stirbet, G.K. Davis, M. A. Drury, C. Grenoble, J. Henry, G. Myneni, T. Powers, K. Wilson, M. Wiseman
    Jefferson Lab, Newport News, Virginia
  • I.E. Campisi, Y.W. Kang, D. Stout
    ORNL, Oak Ridge, Tennessee
  Funding: This work was supported by U.S. DOE contract DE-AC0500R22725.

The Spallation Neutron Source (SNS) makes use of 33 medium beta (0.61) and 48 high beta (0.81) superconducting cavities. Each cavity is equipped with a fundamental power coupler, which should withstand the full klystron power of 550 kW in full reflection for the duration of an RF pulse of 1.3 msec at 60 Hz repetition rate. Before assembly to a superconducting cavity, the vacuum components of the coupler are submitted to acceptance procedures consisting of preliminary quality assessments, cleaning and clean room assembly, vacuum leak checks and baking under vacuum, followed by conditioning and RF high power testing. Similar acceptance procedures (except clean room assembly and baking) were applied for the airside components of the coupler. All 81 fundamental power couplers for SNS superconducting cavity production have been RF power tested at JLAB Newport News and, beginning in April 2004 at SNS Oak Ridge. This paper gives details of coupler processing and RF high power-assessed performances.

TPPT089 Commissioning and Operations Results of the Industry-Produced CESR-Type SRF Cryomodules storage-ring, superconducting-RF, synchrotron, vacuum 4233
  • S.A. Belomestnykh, R.P.K. Kaplan, H. Padamsee, P. Quigley, J.J.R. Reilly, J. Sears, V. Veshcherevich
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  • S. Bauer, M. Pekeler, H. Vogel
    ACCEL, Bergisch Gladbach
  • L.-H. Chang, C.-T. Chen, F.-Z. Hsiao, M.-C. Lin, G.-H. Luo, C. Wang, T.-T. Yang, M.-S. Yeh
    NSRRC, Hsinchu
  • E. Matias, J. Stampe, M.S. de Jong
    CLS, Saskatoon, Saskatchewan
  Funding: Work is partially supported by the National Science Foundation.

Upon signing a technology transfer agreement with Cornell University, ACCEL began producing turn-key 500 MHz superconducting cavity systems. Four such cryomodules have been delivered, commissioned and installed in accelerators for operation to date. Two more cryomodules are scheduled for testing in early 2005. One of them will be put in operation at Canadian Light Source (CLS); the other will serve as a spare at Taiwan Light Source (TLS). The commissioning results and operational experience with the cryomodules in CESR, CLS and TLS are presented.

TOPA009 Photonic Band Gap Accelerator Demonstration at Ku-Band. linac, electron, lattice, acceleration 656
  • E.I. Smirnova, L.M. Earley, R.L. Edwards
    LANL, Los Alamos, New Mexico
  • A.S. Kesar, I. Mastovsky, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts
  Funding: The research is supported by DOE High Energy Physics, Contract No. DE-FG02-91ER40648.

We report progress on the design and cold test of a metal Ku-band PBG accelerator structure. The 17.140 GHz 6-cell PBG accelerator structure with reduced long-range wakefields was designed for the experiment. The copper structure was electroformed and cold-tested. Tuning was performed through chemical etching of the rods. Final cold test measurements were found to be in very good agreement with the design. The structure will be installed on the beam line at the accelerator laboratory at Massachusetts Institute of Technology and will be powered with 3 MW of peak power from the Haimson 17.14 GHz klystron. Results of the design, fabrication, cold test and hot test on the Haimson accelerator will be presented.

TOPE002 Advances in Normal Conducting Accelerator Technology from the X-Band Linear Collider Program collider, linear-collider, linac, gun 204
  • C. Adolphsen
    SLAC, Menlo Park, California
  In the early 1990's, groups at SLAC and KEK began dedicated development of X-band (11.4 GHz) rf technology for a next generation, TeV-scale linear collider. The choice of a relatively high frequency, four times that of the SLAC 50 GeV Linac, was motivated by the cost benefits of having lower rf energy per pulse (hence fewer rf components) and reasonable efficiencies at high gradients (hence shorter linacs). However, to realize such savings requires operation at gradients and peak powers much higher than that hitherto achieved. During the past 15 years, these challenges were met through innovations on several fronts, and resulted in a viable rf system design for a linear collider. This paper reviews these achievements, which include developments in the generation and transport of high power rf, and new insights into high gradient limitations.  
WOAA002 Progress and Plans for R&D and the Conceptual Design of the ILC Main Linacs linac, luminosity, coupling, collider 199
  • H. Hayano
    KEK, Ibaraki
  The International Linear Collider Main Linacs are based on superconducting accelerator structures operating at 1.3 GHz. The basis for this design has been developed and tested at DESY and R&D is progressing at many laboratories around the world including DESY, Orsay, KEK, FNAL, SLAC, Cornell, and JLAB. The status of the TESLA-style cavities and rf system will be reviewed and parameters for the ILC linac will be described. The role of the different linac test facilities will discussed and the critical items and R&D program to support a Conceptual Design and Technical Design will be outlined.  
WPAP001 HELIOS, the Linac Injector of SOLEIL: Installation and First Results linac, gun, electron, emittance 755
  • B. Pottin, R. Chaput, J.-P. Pollina, M.-A. Tordeux
    SOLEIL, Gif-sur-Yvette
  • D. Jousse, J.-L. Pastre, A.S. Setty
    THALES, Colombes
  Funding: SOLEIL

HELIOS is the Hundred MeV Electron Linac Injector Of SOLEIL the new French SR facility. The Linac is constructed by THALES as a “turn key” equipment on the basis of SOLEIL’s APD design. The Linac injector is composed of a triode gun (90 kV, 500 mA), a prebuncher (10 kV, 200 W), a buncher (SW, 15 MeV, 5 MW) focalised by a solenoid and two accelerating sections (TW, 2pi/3, 45 MeV, 12 MW) feeded by 2 klystrons (35 MW). The major Linac components have been previously tested at THALES factory and the installation on the site has begun from October 2004. After a brief description of the building construction, the tests of the Linac components and operating modes will be detailed. The commissioning with beam is planned on March; the results on beam qualities will be presented: energy spread, emittance, and beam dynamics along the Linac.

WPAT003 Glycol-Substitute for High Power RF Water Loads impedance, resonance 841
  • M. Ebert, F.-R. Ullrich
    DESY, Hamburg
  In water loads for high power rf applications, power is dissipated directly into the coolant. Loads for frequencies below approx. 1GHz are ordinarily using an ethylene glycol-water mixture as coolant. The rf systems at DESY utilize about 100 glycol water loads with powers ranging up to 600kW. Due to the increased ecological awareness, the use of glycol is now considered to be problematic. In EU it is forbidden to discharge glycol into the waste water system. In case of cooling system leakages one has to make sure that no glycol is lost. Since it is nearly impossible to avoid any glycol loss in large rf systems, a glycol-substitute was searched for and found. The found sodium-molybdate based substitute is actually a additive for corrosion protection in water systems. Sodium-molybdate is ecologically harmless; for instance, it is also used as fertilizer in agriculture. A homoeopathic dose of 0.4% mixed into deionised water gives better rf absorption characteristics than a 30% glycol mixture. The rf coolant features of this substitute were investigated and tested. The glycol coolant of all rf systems at DESY was substituted. The results of the investigations and tests are presented.  
WPAT005 A New Tuning Module for Resonant Coupling Structures coupling, linac, proton, booster 973
  • V.G. Vaccaro
    Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli
  • T. Clauser, A. Rainò, V. Variale
    INFN-Bari, Bari
  • A. D'Elia
    Naples University Federico II and INFN, Napoli
  • C. De Martinis, D. Giove
    INFN-Milano, Milano
  • M.R. Masullo
    INFN-Napoli, Napoli
  • M. Mauri
    INFN/LASA, Segrate (MI)
  In order to have efficient particle acceleration it is fundamental that the particles experience, in the accelerating gap, field amplitudes as uniform and as high as possible from gap to gap. Because of the unavoidable fabrication errors, an accelerating structure, when assembled, exhibits field values lower than the nominal ones and/or not uniform. All the usual procedures developed in order to adjust the parameter deviations responsible of the malfunction of these structures, are based on field amplitude measurements, by using the bead pull technique, which is a very invasive technique. In this paper the philosophy is reversed: it is assumed that all the information can be got by Sounding the Modes of the whole System (SMS) and correct the deviation of each frequency mode from its nominal value by means of an appropriate tuning of the cavities: resorting to a perturbative technique applied to a circuit model representing this kind of structures, it is possible to calculate the amount of tuning to give to the cavities. It will be shown that a very good equalization and maximization of the fields in the cavities can be achieved by using this technique.  
WPAT006 The SPARC RF Synchronization System laser, gun, feedback, linac 1024
  • A. Gallo, D. Alesini, M. Bellaveglia, R. Boni, G. Di Pirro, F. Tazzioli
    INFN/LNF, Frascati (Roma)
  The SPARC project consists in a 150 MeV Linac aimed at driving an ondulator for the production of 530 nm SASE FEL radiation. A bunch transverse emittance as low as 1mm mrad and a bunch peak current of about 100 A are required for this task. The RF voltages in the RF gun and in the 3 S-band accelerating sections have to be kept phase locked within 3 ps to the arrival time of the laser pulse on the photocathode to guarantee the required performances. This specification will be reduced to 0.5 ps in the phas·10-2 of the project when the rectilinear RF compression of the bunch will be tested. The general architecture of the SPARC RF control system together with some bench qualification measurements of the basic components is presented in this paper.  
WPAT008 Recent Status of RF Source in J-PARC Linac linac, proton, power-supply, site 1123
  • E. Chishiro, T. Hori, H. Suzuki, M. Yamazaki
    JAERI, Ibaraki-ken
  • S. Anami, S. Fukuda, Y. Fukui, M. Kawamura, S. Yamaguchi, M. Yoshida
    KEK, Ibaraki
  The construction of the J-PARC (Japan Proton Accelerator Research Complex) linac is under going. RF sources for the low beta linac section use 324-MHz klystrons and after the evaluation of seven prototype tubes, mass production of 20 tubes are conducted. These will be installed in the linac building from April 2005. Performances of the 324-MHz klystrons are described in this paper. The prototype klystron of 972-MHz klystron, which is planed to be installed in high beta linac section, oscillated strongly without any drive rf power, and it had been investigated to solve it. Though it was doubted to be a diode oscillation at first, recent experiment showed the drift-tube oscillation and we succeeded in stopping oscillation by deforming the integrated cavity and detuning. After this experiment, we built a new tube and started to test it. This experiment is written in this paper. Other status of construction related to the rf sources is also shown in this paper.  
WPAT012 Status and Test Results of HPRF System for PEFP rfq, proton, pick-up, ion-source 1288
  • K.T. Seol, Y.-S. Cho, H.-S. Kim, H.-J. Kwon, M.-Y. Park, Y.G. Song
    KAERI, Daejon
  Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government.

The PEFP 20MeV proton accelerator is composed of 3MeV RFQ and 20MeV DTL and two sets of 1MW, 350MHz RF system are required for each accelerating structure. The high power RF system for 3MeV RFQ was already installed and operated to drive the RFQ. The klystron was tested up to 600kW itself and operated in pulse routinely. The HPRF system for 20MeV DTL which consists of 4 tanks was installed, and the RF test for 4 tanks has been carried out. The ridge-loaded power coupler was designed and installed to drive RFQ and DTL. In this paper, the status and test results of the RF system for 20MeV proton accelerator are discussed.

WPAT014 Sequence Control System of 1-MW CW Klystron for the PEFP power-supply, rfq, proton, ion 1401
  • B.R. Park, J. Choi, M.-H. Chun, Y.J. Han, M.H. Jeong, S.-C. Kim, J.S. Yang, I.H. Yu
    PAL, Pohang, Kyungbuk
  Funding: Work support by the PEFP(Proton Engineering Frontier Project), Korea.

Sequence control system of 1-MW CW klystron for the PEFP (Proton Engineering Frontier Project) has been developed in order to drive the 1-MW klystron amplifier. The system is able to control several power supplies and many environment conditions. The hardware of sequence control and the interlock system are based on the Allen-Bradley's SLC500 Program Logic Controller (PLC). Also the system can be controlled by a touch screen at local mode or Ethernet network with high level HMI at remote mode.

WPAT031 Design and Operation of a High Power L-Band Multiple Beam Klystron electron, cathode, focusing, higher-order-mode 2170
  • A. Balkcum, H.P. Bohlen, M. Cattelino, L. Cox, M. Cusick, S. Forrest, F. Friedlander, A. Staprans, E.L. Wright, L. Zitelli
    CPI, Palo Alto, California
  • K. Eppley
    SAIC, Burlington, Massachusetts
  A 1.3 GHz, 10 MW, higher-order-mode multiple beam klystron (MBK) has been developed for the TESLA program. The relative advantages of such a device are many-fold. Multiple beams generate higher beam currents and thereby require much lower operating voltages which allows for the use of smaller, less expensive modulators. A lower perveance per cathode can also be used which leads to higher operating efficiencies. Higher-order-mode cavities allow for the use of much larger cathodes which leads to lower cathode current density loadings and subsequently longer cathode lifetimes. This requires that the cathodes be located far off the geometric axis of the device. The compromise is an increase in the complexity of the magnetic focusing circuit required to transport the off-axis electron beams. Such a device has been successfully built and tested. Excellent beam transmission has been achieved (99.5% DC and 98% at RF saturation). A peak power of 10 MW with 150 kW of average power and 60% efficiency, 49 dB gain have also been measured. The achieved low cathode loading of 2.1 A/cm2 corresponds to an expected cathode life of over 140,000 operational hours.  
WPAT032 Large Scale Production of 805-MHz Pulsed Klystrons for the Spallation Neutron Source Project SNS, gun, cathode, Spallation-Neutron-Source 2230
  • S. Lenci, E.L. Eisen
    CPI, Palo Alto, California
  The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built in Oak Ridge, Tennessee, by the U.S. Department of Energy. CPI is supporting the effort by providing 81 pulsed klystrons for the super-conducting portion of the accelerator. The primary output power requirements are 550 kW peak, 49.5 kW average at 805 MHz, with an electron beam-to-rf conversion efficiency of 65% and an rf gain of 50 dB. Through December 2004, 77 units have been factory-tested. Performance specifications, computer model predictions, operating results, and production statistics will be presented.  
WPAT035 The LANSCE 805 MHZ RF System History and Status acceleration, focusing, power-supply 2402
  • M.T. Lynch, G. Bolme, P.J. Tallerico
    LANL, Los Alamos, New Mexico
  The Los Alamos Neutron Science Center (LANSCE) linear accelerator runs at 201.25 MHz for acceleration to 100 MeV. The remainder of the acceleration to 800 MeV is at 805 MHz. This is done with 44 accelerator cavity stages driven by 805 MHz klystrons. Each klystron has a peak power capability of 1.25 MeV. Originally, 97 klystrons were purchased, which was 70 from Varian/CPI and 27 from Litton. The 44 RF systems are laid out in sectors with either 6 or 7 klystrons per sector. The klystrons in each sector are powered from a common HV sytem. The current arrangement uses the Varian/CPI klystrons in 6 of the 7 sectors and Litton klystrons in the remaining sector. With that arrangement there are 38 CPI klystrons installed and 1 spare klystron per sector and 6 Litton klystrons installed in the final sector with 2 spares. The current average life of all of the operating and spare klystrons (52 total) is >112,000 filament hours and >93,000 HV hours. That is three times the typical klystron lifetime today for other similar klystrons. This paper summarizes the details of the LANSCE klystron history and status and a summary of the predicted failure rate.  
WPAT036 A 700 MHZ, 1 MW CW RF System for a FEL 100mA RF Photoinjector power-supply, cathode, vacuum, coupling 2413
  • W. Roybal, D.C. Nguyen, W. Reass, D. Rees, P.J. Tallerico, P.A. Torrez
    LANL, Los Alamos, New Mexico
  Funding: U.S. Department of Energy.

This paper describes a 700 MHz, 1 Megawatt CW, high efficiency klystron RF system utilized for a Free Electron Laser (FEL) high-brightness electron photoinjector (PI). The E2V klystron is mod-anode tube that operates with a beam voltage of 95 kV. This tube, operating with a 65% efficiency, requires ~96 watts of input power to produce in excess of 1 MW of output power. This output drives the 3rd cell of a 2-cell, p-mode PI cavity through a pair of planar waveguide windows. Coupling is via a ridge-loaded tapered waveguide section and "dog-bone" iris. This paper will present the design of the RF, RF transport, coupling, and monitoring/protection systems that are required to support CW operations of the 100 mA cesiated, semi-porous SiC photoinjector.

WPAT037 LANSCE RF System Refurbishment linac, proton, SNS, diagnostics 2476
  • D. Rees, G. Bolme, S.I. Kwon, J.T.M. Lyles, M.T. Lynch, M. Prokop, W. Reass, P.J. Tallerico
    LANL, Los Alamos, New Mexico
  The Los Alamos Neutron Science Center (LANSCE) is in the planning phase of a refurbishment project that will sustain reliable facility operations well into the next decade. The LANSCE accelerator was constructed in the late 1960s and early 1970s and is a national user facility that provides pulsed protons and spallation neutrons for defense and civilian research and applications. We will be replacing all the 201 MHz RF systems and a substantial fraction of the 805 MHz RF systems and high voltage systems. The current 44 LANSCE 805 MHz, 1.25 MW klystrons have an average in-service time in excess of 110,000 hours. All 44 must be in service to operate the accelerator. There are only 9 spares left. The klystrons receive their DC power from the power system originally installed in 1960. Although this power system has been extremely reliable, gas analysis of the insulating oil is indicating age related degradation that will need attention in the next few years. This paper will provide the design details of the new RF and high voltage systems.  
WPAT039 Experience with the New Digital RF Control System at the CESR Storage Ring feedback, synchrotron, storage-ring, vacuum 2592
  • M. Liepe, S.A. Belomestnykh, J. Dobbins, R.P.K. Kaplan, C.R. Strohman, B.K. Stuhl
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  Funding: This work is supported by NSF.

A new digital control system has been developed, providing great flexibility, high computational power and low latency for a wide range of control and data acquisition applications. This system is now installed in the CESR storage ring and stabilizes the vector sum field of two of the superconducting CESR 500 MHz cavities and the output power from the driving klystron. The installed control system includes in-house developed digital and RF hardware, very fast feedback and feedforward control, a state machine for automatic start-up and trip recovery, cw and pulsed mode operation, fast quench detection, and cavity frequency control. Several months of continuous operation have proven high reliability of the system. The achieved field stability surpasses requirements.

WPAT040 Pushing the Limits: RF Field Control at High Loaded Q linac, resonance, beam-loading, feedback 2642
  • M. Liepe, S.A. Belomestnykh, J. Dobbins, R.P.K. Kaplan, C.R. Strohman, B.K. Stuhl
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  • C. Hovater, T. Plawski
    Jefferson Lab, Newport News, Virginia
  Funding: This work is supported by Cornell University.

The superconducting cavities in an Energy-Recovery-Linac will be operated with a high loaded Q of several 1E7, possible up to 1E8. Not only has no prior control system ever stabilized the RF field in a linac cavity with such high loaded Q, but also highest field stability in amplitude and phase is required at this high loaded Q. Because of a resulting bandwidth of the cavity of only a few Hz, this presents a significant challenge: the field in the cavity extremely sensitive to any perturbation of the cavity resonance frequency due to microphonics and Lorentz force detuning. To prove that the RF field in a high loaded Q cavity can be stabilized, and that Cornell's newly developed digital control system is able to achieve this, the system was connected to a high loaded Q cavity at the JLab IR-FEL. Excellent cw field stability – about 2·10-4 rms in relative amplitude and 0.03 deg rms in phase - was achieved at a loaded Q of 2.1·107 and 1.4E8, setting a new record in high loaded Q operation of a linac cavity. Piezo tuner based cavity frequency control proved to be very effective in keeping the cavity on resonance and allowed reliable to ramp up to high gradients in less than 1 second.

WPAT041 Klystron Linearizer for Use with 1.2 MW 476 MHz Klystrons in PEP-II RF Systems feedback, impedance, monitoring, radio-frequency 2660
  • J.D. Fox, T. Mastorides, D. Teytelman, D. Van Winkle, Y.-B. Zhou
    SLAC, Menlo Park, California
  • A. Gallo
    INFN/LNF, Frascati (Roma)
  Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515.

The direct and comb loop feedback around the RF cavities in PEP-II is critical in reducing longitudinal instabilities driven by the cavity impedance, and the non-linear 1 MW klystron is in the signal path for these feedback loops. As a result, the effective small-signal gain of the klystron at 85% saturation reduces the impedance control by factors of 5 to 20 as compared to a linear power amplifier. A klystron linearizer circuit has been developed which operates in series with the power amplifier and acts to equalize the small and large signal gains through the combination. The technique must implement a 1 MHz linear control bandwidth over roughly 15 dB of RF signal level variation. The dynamics of this system is operating point dependent, and the channel must have dynamic gain compensation to keep the linearity compensation loop stable over changes in operating point. The design of this non-linear signal processing channel (incorporating RF and DSP techniques) and measured results from full-power klystron testing are presented.

WPAT043 Overview of the RF Systems for LCLS linac, gun, feedback, undulator 2753
  • P.A. McIntosh, R. Akre, R.F. Boyce, P. Emma, S. Hill, E. Rago
    SLAC, Menlo Park, California
  Funding: Work supported by Department of Energy contract DE-AC03-76SF00515.

The Linac Coherent Light Source (LCLS) at SLAC, when it becomes operational in 2009, will provide its user community with an X-ray source many orders of magnitude brighter than anything available in the world at that time. The electron beam acceleration will be provided by existing and new RF systems capable of maintaining the amplitude and phase stability of each bunch to extremely tight tolerances. RF feedback control of the various RF systems will be fundamental in ensuring the beam arrives at the LCLS undulator at precisely the required energy and phase. This paper details the requirements for RF stability for the various LCLS RF systems and also highlights proposals for how these injector and Linac RF systems can meet these constraints.

WPAT044 Realization of an X-Band RF System for LCLS linac, vacuum, linear-collider, collective-effects 2801
  • P.A. McIntosh, R. Akre, J. Brooks, P. Emma, E. Rago
    SLAC, Menlo Park, California
  Funding: Work supported by Department of Energy contract DE-AC03-76SF00515.

A single X-band (11.424 GHz) accelerating structure is to be incorporated in the LCLS Linac design to linearize the energy-time correlation (or gradient) across each bunch, features which originate in the preceding accelerating structures (L0 and L1). This harmonic RF system will operate near the negative RF crest to decelerate the beam, reducing these non-linear components of the correlation, providing a more efficient compression in the downstream bunch compressor chicanes (BC1 and BC2). These non-linear correlation components, if allowed to grow, would lead to Coherent Synchrotron Radiation (CSR) instabilities in the chicanes, effectively destroying the coherence of the photon radiation in the main LCLS undulator. The many years devoted at SLAC in the development of X-band RF components for the NLC/JLC linear collider project, has enabled the technical and financial realization of such an RF system for LCLS. This paper details the requirements for the X-band system and the proposed scheme planned for achieving those requirements.

WPAT045 A Non-Invasive Technique for Configuring Low Level RF Feedback Loops in PEP-II feedback, impedance, extraction, collider 2863
  • D. Teytelman
    SLAC, Menlo Park, California
  Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515.

The RF system of the PEP-II collider uses two fast feedback loops around each klystron and set of cavities. These loops reduce the impedance of the fundamental mode of the accelerating cavities seen by the beam, and are necessary to reduce the growth rates of longitudinal modes within the RF system bandwidth. Operation of the accelerator at high beam currents is very sensitive to the configuration of the low-level RF feedback loops. There are 7 loop control parameters that strongly influence the stability of the feedback loops and the achieved level of longitudinal impedance reduction. Diagnostic techniques for the analysis of the RF feedback via closed-loop system transfer function measurements will be presented. The model is fit to the measured closed-loop transfer function data and the extracted parameters are then used to calculate optimal tuning and corrections to the loop control elements in the physical channel. These techniques allow fine-tuning of RF feedback with stored beam as well as diagnosis of mis-configured or malfunctioning elements of the system. Results from PEP-II operation will be presented to illustrate the techniques and their applications.

WPAT047 Solid-State 2MW Klystron Power Control System cathode, controls, vacuum, power-supply 2950
  • M.A. Kempkes, J.A. Casey, M.P.J. Gaudreau, T.H. Hawkey, I. Roth
    Diversified Technologies, Inc., Bedford
  Under an SBIR effort for the DOE, Diversified Technologies, Inc. designed, built, and installed a solid state power control system for the Advanced Light Source klystrons at Argonne National Laboratory (ANL). This system consists of two major elements – a 100 kV, 20 A CW solid state series switch, and a solid state voltage regulator for the mod-anode of the klystron. The series switch replaces the existing mercury ignitron crowbar, eliminating these environmentally hazardous components while providing enhanced arc protection and faster return to transmit. The mod-anode voltage regulator uses series IGBTs, operating in the linear regime, to provide highly rapid and accurate control of the mod-anode voltage, and therefore the output power from the klystron. Results from the installation and testing of this system at ANL will be presented.  
WPAT050 High Power Phase Shifter resonance, linac, proton, power-supply 3123
  • I. Terechkine, G.W. Foster, I.G. Gonin, T.K. Khabiboulline, A. Makarov, N. Solyak, D. Wildman
    Fermilab, Batavia, Illinois
  One of the approaches to power distribution system of a superconducting proton linac that is under discussion at Fermilab requires development of a fast-action, megawatt-range phase shifter. Using two phase shifters with a waveguide hybrid junction can allow independent control of phase and amplitude of RF power at the input of each superconducting cavity of the linac. This promises significant saving in number of klystrons and modulators required for the accelerator. A prototype of a waveguide version of a phase shifter that uses Yttrium-Iron Garnet (YIG) blocks was developed and tested. This report presents design concept of the device and main results of simulation and proof-of-principle tests.  
WPAT051 Development of Toshiba L-Band Multi-Beam Klystron for European XFEL Project cathode, gun, electron, simulation 3153
  • Y.H. Chin
    KEK, Ibaraki
  • S. Choroba
    DESY, Hamburg
  • M. Y. Miyake, Y. Yano
    Toshiba, Yokohama
  A 10MW L-band multi-beam klystron (MBK)is under develpment at Toshiba, Japan for DESY X-FEL and a future linear collider projects. The design goals are to have 10MW peak power with 65% efficiency at 1.5 ms pulse length at 10Hz repetition rates. The Toshiba MBK has six low-perveance beams operated at low voltage of 115kV (for 10MW) to enable a higher efficiency than a single-beam klystron for a similar power. The prototyp·10-0 has been built and is now under testing. At the first step, it was tested without RF and operates stably at the cathode voltage of 115KV at 1.7ms pulse length at 10Hz repetition rate with beam transmission of better than 99%. No spurious oscillation was observed. The testing is now progressed with RF on. Up to date of November 10, 2004, The output power of 10.3MW has been demonstrated at the beam voltage of 115kV with efficinecy of 68.4% at the RF pulse length of 1ms at 10Hz. The testing is under way to increase the RF pulse length to the goal value of 1.5ms. This paper summarizes the design and the testing results.  
WPAT053 Results of a High-Power Klystron Dip Test in the KEK Linac cathode, linac, injection, space-charge 3235
  • K. Nakao, S. Fukuda, H. Katagiri, T. Matsumoto, S. Michizono, T. Takenaka, Y. Yano, M. Yoshida
    KEK, Ibaraki
  Dip test, which is the measurement of a klystron heater activity, is recently adopted as the standard measurement to maintain the klystron operation in the KEK electron-positron linac. In 2003, we began to use a dip test as the quick way to measure the emission characteristics from the klystron cathode. After the successful results, we made the dedicated measuring systems and measured the dips of the cathode emission of 60 operating klystrons in KEK electron-positron linac. These data are important to estimate the klystron cathode life and used to select the candidate klystrons of replacement in the summer maintenance period.  
WPAT054 5 MW 805 MHz SNS RF System Experience vacuum, SNS, shielding, linac 3280
  • K.A. Young, J.T. Bradley, T.W. Hardek, M.T. Lynch, D. Rees, W. Roybal, P.J. Tallerico, P.A. Torrez
    LANL, Los Alamos, New Mexico
  Funding: Work supported by the U.S. DOE.

The RF system for the 805 MHz normal conducting linac of the Spallation Nuetron Source (SNS) accelerator was designed, procured and tested at Los Alamos National Laboratory(LANL) and then installed and commissioned at Oak Ridge National Laboratory (ORNL). The RF power for this room temperature coupled cavity linac (CCL) of SNS accelerator is generated by four pulsed 5 MW peak power klystrons operating with a pulse width of 1.25 mSec and a 60 Hz repetition frequency. The RF power from each klystron is divided and delivered to the CCL through two separate RF windows. The 5 MW RF system advanced the state of the art for simultaneous peak and average power. This paper summarizes the problems encountered, lessons learned and results of the high power testing at LANL of the 5 MW klystrons, 5 MW circulators, 5 MW loads, and 2.5 MW windows.*

*Tom Hardek is now at ORNL.

WPAT055 Enhancements for the 1 MW High Voltage Converter Modulator Systems at the SNS SNS, cathode, linac, resonance 3313
  • D.E. Anderson, J. Hicks, D. E. Hurst, E.R. Tapp, M. Wezensky
    ORNL, Oak Ridge, Tennessee
  • D. Baca, W. Reass
    LANL, Los Alamos, New Mexico
  • V.V. Peplov
    RAS/INR, Moscow
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

The first-generation high frequency switching megawatt-class high voltage converter modulators (HVCM) developed by Los Alamos National Laboratory for the Spallation Neutron Source at Oak Ridge National Laboratory have been installed and are now operational. Each unit is capable of delivering pulses up to 11 MW peak, 1 MW average power at voltages up to 140 kV to drive klystron(s) rated up to 5 MW. To date, three variations of the basic design have been installed, each optimized to deliver power to a specific klystron load configuration. Design improvements, with the primary intention of improving system reliability and availability, have been under development since the initial installation of the HVCM units. This paper will examine HVCM reliability studies, reliability operational data, and modifications and improvements performed to increase the overall system availability. We will also discuss system enhancements aimed at improving the ease of operation and providing for additional equipment protection features.

WPAT057 Overview of the Spallation Neutron Source Linac Low-Level RF Control System linac, SNS, Spallation-Neutron-Source, feedback 3396
  • M. Champion, M.T. Crofford, K.-U. Kasemir, H. Ma, M.F. Piller
    ORNL, Oak Ridge, Tennessee
  • L.R. Doolittle, A. Ratti
    LBNL, Berkeley, California
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

The design and production of the Spallation Neutron Source Linac Low-Level RF control system is complete, and installation will be finished in Spring 2005. The warm linac beam commissioning run in Fall 2004 was the most extensive test to date of the LLRF control system, with fourteen (of an eventual 96) systems operating simultaneously. In this paper we present an overview of the LLRF control system, the experience in designing, building and installing the system, and operational results.

WPAT058 Operational Experience with the Spallation Neutron Source High Power Protection Module SNS, linac, monitoring, Spallation-Neutron-Source 3411
  • M.T. Crofford, M. Champion, K.-U. Kasemir, H. Ma, M.F. Piller
    ORNL, Oak Ridge, Tennessee
  The Spallation Neutron Source (SNS) High Power Protection Module provides protection for the High Power RF Klystron and Distribution System and interfaces with the Low-Level Radio-Frequency (LLRF) Field Control Module (FCM). The fault detection logic is implemented in a single FPGA allowing modifications and upgrades to the logic as we gain operational experience with the LINAC RF systems. This paper describes the integration and upgrade issues we have encountered during the initial operations of the SNS systems.  
WPAT059 High Power RF Test Facility at the SNS SNS, vacuum, linac, monitoring 3450
  • Y.W. Kang, D.E. Anderson, I.E. Campisi, M. Champion, M.T. Crofford, R.E. Fuja, P.A. Gurd, S. Hasan, K.-U. Kasemir, M.P. McCarthy, D. Stout, J.Y. Tang, A.V. Vassioutchenko, M. Wezensky
    ORNL, Oak Ridge, Tennessee
  • G.K. Davis, M. A. Drury, T. Powers, M. Stirbet
    Jefferson Lab, Newport News, Virginia
  RF Test Facility has been completed in the SNS project at ORNL to support test and conditioning operation of RF subsystems and components. The system consists of two transmitters for two klystrons powered by a common high voltage pulsed converter modulator that can provide power to two independent RF systems. The waveguides are configured with WR2100 and WR1150 sizes for presently used frequencies: 402.5 MHz and 805 MHz. Both 402.5 MHz and 805 MHz systems have circulator protected klystrons that can be powered by the modulator capable of delivering 11 MW peak and 1 MW average power. The facility has been equipped with computer control for various RF processing and complete dual frequency operation. More than forty 805 MHz fundamental power couplers for the SNS superconducting linac (SCL) cavitites have been RF conditioned in this facility. The facility provides more than 1000 ft2 floor area for various test setups. The facility also has a shielded cave area that can support high power tests of normal conducting and superconducting accelerating cavities and components.

SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

WPAT061 Spallation Neutron Source High Power RF Installation and Commissioning Progress SNS, linac, rfq, Spallation-Neutron-Source 3520
  • M.P. McCarthy, D.E. Anderson, R.E. Fuja, P.A. Gurd, T.W. Hardek, Y.W. Kang
    ORNL, Oak Ridge, Tennessee
  • J.T. Bradley, D. Rees, W. Roybal, K.A. Young
    LANL, Los Alamos, New Mexico
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

The Spallation Neutron Source (SNS) linac will provide a 1 GeV proton beam for injection into the accumulator ring. In the normal conducting (NC) section of this linac, the Radio Frequency Quadupole (RFQ) and six drift tube linac (DTL) tanks are powered by seven 2.5 MW, 402.5 MHz klystrons and the four coupled cavity linac (CCL) cavities are powered by four 5.0 MW, 805 MHz klystrons. Eighty-one 550 kW, 805 MHz klystrons each drive a single cavity in the superconducting (SC) section of the linac. The high power radio frequency (HPRF) equipment was specified and procured by LANL and tested before delivery to ensure a smooth transition from installation to commissioning. Installation of RF equipment to support klystron operation in the 350-meter long klystron gallery started in June 2002. The final klystron was set in place in September 2004. Presently, all RF stations have been installed and high power testing has been completed. This paper reviews the progression of the installation and testing of the HPRF Systems.

WPAT062 The Spallation Neutron Source RF Reference System SNS, linac, rfq, Spallation-Neutron-Source 3573
  • M.F. Piller, M. Champion, M.T. Crofford, H. Ma
    ORNL, Oak Ridge, Tennessee
  • L.R. Doolittle
    LBNL, Berkeley, California
  The Spallation Neutron Source (SNS) RF Reference System includes the master oscillator (MO), local oscillator(LO) distribution, and Reference RF distribution systems. Coherent low noise Reference RF signals provide the ability to control the phase relationships between the fields in the front-end and linear accelerator (linac) RF cavity structures. The SNS RF Reference System requirements, implementation details, and performance are discussed.  
WPAT071 R&D Status of the 700 MHz, 1MW Klystron for PEFP cathode, gun, coupling, proton 3850
  • S.-H. Kim, B.H. Chung, K.-H. Chung, J.-S. Hong, J.-H. Jeon, sk. Ko, K. Lee, sj. Noh
    KAPRA, Cheorwon
  Funding: This study is supported by Proton Engineering Frontier Project at Korea Atomic Energy Research Institute.

KAPRA (Korea Accelerator and Plasma Research Association) are undertaking the first phase R&D for the 1 MW, CW 700 MHz klystron, which is targeting the future stage of the PEFP (Proton Engineering Frontier Project) accelerator at KAERI (Korea Atomic Energy Research Institute). The objectives of the first phase R&D are 1) setting up all infra structures/procedures for the design and fabrication, 2) developing a prototype klystron for proofs of principles, and 3) making a performance test of the prototype at a reduced duty. The second phase R&D is supposed to cover full power, CW operation and reliability issues. In this paper, a summary of R&D Status during the first phase for PEFP 1 MW, 700 MHz klystron is reported.

WPAT074 In Depth Diagnostics for RF System Operation in the PEP-II B Factory diagnostics, monitoring, feedback, beam-losses 3931
  • D. Van Winkle, J.D. Fox, D. Teytelman
    SLAC, Menlo Park, California
  Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515.

The PEP-II RF systems incorporate numerous feedback loops in the low-level processing for impedance control and operating point regulation. The interaction of the multiple loops with the beam is complicated, and the systems incorporate online diagnostic tools to configure the feedback loops as well as to record fault files in the case of an RF abort. Rapid and consistent analysis of the RF-related beam aborts and other failures is critical to the reliable operation of the B-Factory, especially at the recently achieved high beam currents. Procedures and algorithms used to extract diagnostic information from time domain fault files are presented and illustrated via example interpretations of PEP-II fault file data. Example faults presented will highlight the subtle interpretation required to determine to root cause. Some such examples are: abort kicker firing asynchronously, klystron and cavity arcs, beam loss leading to longitudinal instability, tuner read back jumps and poorly configured low-level RF feedback loop.

WPAT075 Design and Calibration of a Phase and Amplitude Detector linac, shielding, radiation
  • Z. Geng, P. Gu, H.Mi. Hou, G. Pei
    IHEP Beijing, Beijing
  The phase and amplitude detector (PAD) is a key unit of the phasing system for BEPCII linac. One of the main functions of the PAD is to measure the phase of each klystron accurately from such large noises. To meet the need of the phasing system, a new PAD is constructed based on I/Q demodulator and industrial computer. But the I/Q demodulator suffers form phase and amplitude mismatch, which can draw big error on phase measurement. In order to compensate the mismatch of the I/Q demodulator, we develop a calibration program using an adaptive method, LMS method. Almost all the mismatches of the I/Q demodulator are compensated after calibration.  
WPAT080 Calculation of Beam-Loaded Q in High-Power Klystrons gun, vacuum, bunching, cathode 4060
  • J.F. DeFord, B. H. Held
    STAR, Inc., Mequon, Wisconsin
  • V. Ivanov, K. Ko
    SLAC, Menlo Park, California
  Funding: Work supported by DOE SBIR Grant DE-FG02-03ER83776.

Instabilities in the gun region of a high-power klystron can occur when there is positive feedback between a mode and an induced current on the quasi-steady state beam emitted by the gun cathode.* This instability is dependent on the gun voltage, is predicted on the basis of a negative beam-loaded Q. The established method for computing the beam-loaded Q of a cavity involves using a time-dependent electromagnetic particle-in-cell (PIC) code to track beam particles through the quasi-static gun fields perturbed by the electromagnetic fields of a cavity eigenmode.** The energy imparted to the beam by the mode is obtained by integrating the Lorentz force along the particle tracks, and this quantity is simply related to the beam-loaded Q. We have developed an alternative approach that yields comparable accuracy but is computationally much simpler. The new method is based on a much simpler time-independent electrostatic PIC calculation, resulting in much faster solutions without loss of accuracy. We will present the theory and implementation of the new method, as well as benchmarks and results from analysis of the XP-4 klystron that show a potential instability near 3 GHz.

*B. Krietenstein, et al., "Spurious oscillations in high-power klystrons," PAC95, 1995. **U. Becker, et al., "Simulation of oscillations in high-power klystrons," EPAC, 1996.

RPPE003 Operational Experience of Cooling Water Systems for Accelerator Components at PLS linac, storage-ring, power-supply, higher-order-mode 850
  • K.R. Kim, C.W. Chung, H.S. Han, H.-G. Kim, Y.-C. Kim, I.S. Ko, B.H. Lee
    PAL, Pohang, Kyungbuk
  Funding: Work supported by MOST and POSCO in Republic of Korea.

The cooling water system has been utilized for absorbing heat generated by a multitude of electromagnetic power delivering networks at PLS. The separate cooling water distribution systems for the storage ring, beam transport line and linear accelerator have been operated with a different operating temperature of supplying water. All water used for heat removal from the accelerator components are deionised and filtered to provide with over 2 MO-cm specific resistance. The operating pressures and flows of input water are also controlled with flow balancing scheme at a specified range. The operating temperature of components in the accelerator is sustained as tight as below ±0.1 deg C to minimize the influence of temperature fluctuation on the beam energy and stability. Although the PLS cooling systems were initially installed with a high degree of flexibility to allow for easy maintenance, a number of system improvements have been employed to enhance operational reliability and to incorporate the newly developed operating interfaces such as EPICS accelerator control systems. The important design and operational features of PLS cooling water systems are presented as well as lessons learned from around 10-years normal operation.

RPPE012 Grounding of SNS Accelerator Structure SNS, linac, impedance, instrumentation 1278
  • P.S. Holik
    ORNL, Oak Ridge, Tennessee
  Funding: UT-Battelle, SNS Collaboration.

Description of site general grounding network. RF grounding network enhancement underneath the klystron gallery building. Grounding network of the Ring Systems with ground breaks in the Ring Tunnel. Grounding and Bonding of R&D accelerator equipment. SNS Building lightning protection.


RPPE060 Overview of SNS Cryomodule Performance SNS, vacuum, linac, resonance 3496
  • M. A. Drury, E. Daly, G.K. Davis, J.R. Delayen, C. Grenoble, W.R. Hicks, K. King, T. Plawski, T. Powers, J.P. Preble, H. Wang, M. Wiseman
    Jefferson Lab, Newport News, Virginia
  Funding: Supported by U.S. DOE Contract Nos. DE-AC05-84ER40150.

Thomas Jefferson National Accelerating Facility (Jefferson Lab) has completed production of 24 Superconducting Radio Frequency (SRF) cryomodules for the Spallation Neutron Source (SNS) superconducting linac. This includes one medium-beta (0.61) prototype, eleven medium-beta and twelve high-beta (0.81) production cryomodules. Ten medium-beta cryomodules as well as two high beta cryomodules have undergone complete operational performance testing in the Cryomodule Test Facility at Jefferson Lab. The set of tests includes measurements of maximum gradient, unloaded Q (Q0), microphonics, and response to Lorentz forces. The Qext’s of the various couplers are measured and the behavior of the higher order mode couplers is examined. The mechanical and piezo tuners are also characterized. The results of these performance tests will be discussed in this paper.

RPPP002 RF Sources of Super-Conducting Test Facility (STF) at KEK linac, feedback, proton, linear-collider 796
  • S. Fukuda, H. Hayano
    KEK, Ibaraki
  After the ITRP’s technical choice, KEK tried to seek the contribution for the international linear collider and made the plan of super-conducting test facility (STF) in KEK. The STF comprised of phase-I and phase-II; former is the plan for two years from FY2005 and aimed for the quick construction of test facility to evaluate the 4-35MV/m cavity structures and 4-45 MV/m cavity structures with a beam. Phase-II is the next plan of the test facility to extend the several 17m cryomodules. In this paper, general description of the STF is made at first, and rf source plan is shown.  
RPPT013 Status of the SPARC Project laser, gun, emittance, undulator 1327
  • L. Serafini, F. Alessandria, A. Bacci, S. Cialdi, C. De Martinis, D. Giove, M. Mauri, M. Rome, L. Serafini
    INFN-Milano, Milano
  • D. Alesini, M. Bellaveglia, S. Bertolucci, M.E. Biagini, R. Boni, M. Boscolo, M. Castellano, A. Clozza, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, S. Guiducci, M. Incurvati, C. Ligi, F. Marcellini, M.  Migliorati, A. Mostacci, L. Palumbo, L. Pellegrino, M.A. Preger, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, F. Tazzioli, C. Vaccarezza, M. Vescovi, C. Vicario
    INFN/LNF, Frascati (Roma)
  • I. Boscolo, C. Maroli, V. Petrillo
    Universita' degli Studi di Milano, MILANO
  • F. Broggi
    INFN/LASA, Segrate (MI)
  • L. Catani, E. Chiadroni, A. Cianchi, E. Gabrielli, S. Tazzari
    INFN-Roma II, Roma
  • F. Ciocci, G. Dattoli, A. Dipace, A. Doria, F. Flora, G.P. Gallerano, L. Giannessi, E. Giovenale, G. Messina, P.L. Ottaviani, S. Pagnutti, G. Parisi, L. Picardi, M. Quattromini, A. Renieri, G. Ronci, C. Ronsivalle, M. Rosetti, E. Sabia, M. Sassi, A. Torre, A. Zucchini
    ENEA C.R. Frascati, Frascati (Roma)
  • D. Dowell, P. Emma, C. Limborg-Deprey, D.T. Palmer
    SLAC, Menlo Park, California
  • D. Levi, M. Mattioli, G. Medici, P. Musumeci, D. Pelliccia
    Università di Roma I La Sapienza, Roma
  • M. Nisoli, S. Stagira, S. de Silvestri
    Politecnico/Milano, Milano
  • M. Petrarca
    INFN-Roma, Roma
  • J.B. Rosenzweig
    UCLA, Los Angeles, California
  The SPARC project has entered its installation phase at INFN-LNF: its main goal is the promotion of an R&D activity oriented to the development of a high brightness photoinjector to drive SASE-FEL experiments. The design of the 150 MeV photoinjector has been completed and the construction of its main components is in progress, as well as the design of the 12 m undulator. In this paper we will report on the installation and test of some major components, like the Ti:Sa laser system to drive the photo-cathode, the RF gun, the RF power system, as well as some test results on the RF deflector and 4th harmonic X-band cavity prototypes. Advancements in the control and beam diagnostics systems will also be reported, in particular on the emittance-meter device for beam emittance measurements in the drift space downstream the RF gun. Recent results on laser pulse shaping, obtained with two alternative techniques (DAZZLER and Liquid Crystal Mask), show the feasibility of producing 10 ps flat-top laser pulses in the UV with rise time below 1 ps, as needed to maximize the achievable beam brightness. First FEL experiments have been proposed, using SASE, seeding and non-linear resonant harmonics: these will be briefly described.  
RPPT036 200 MeV Linac Upgrade for FEL linac, gun, electron, cathode 2464
  • Y.G. Zhou, S. Dong, H. He, L.G. Li
    USTC/NSRL, Hefei, Anhui
  The present status of Hefei 200 MeV RF linac are given. By upgrading its present thermal cathode system into the photo cathode system and implement RF phase locked system, using Hefei 200 MeV RF linac as FEL driver is investigated.  
ROPC007 Status of the Proton Engineering Frontier Project proton, rfq, linac, beam-transport 576
  • B.H. Choi
    KAERI, Daejon
  Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government.

The Proton Engineering Frontier Project (PEFP) approved and launched by the Korean government in July 2002 includes a 100MeV proton linear accelerator development and a program for its utilization. The first phase of the project, running from 2002 to 2005, was the design of a 100MeV proton linear accelerator and a part of development to 20 MeV. This consists of a 50 keV proton injector, a 3 MeV radio frequency quadrupole (RFQ), and a 20MeV drift tube linac (DTL). The 50 keV injector and the 3 MeV RFQ has been installed and tested, and the 20 MeV DTL is being assembled and tuned for beam tests. At the same time, the utilization programs using the proton beam have been planned, and some are now under way. The status and progress of the project are reported in detail.

FPAE044 Test Results of the PEFP 3MeV RFQ Upgrade rfq, proton, coupling, dipole 2842
  • Y.-S. Cho, S.-H. Han, J.-H. Jang, H.-S. Kim, Y.-H. Kim, H.-J. Kwon, M.-Y. Park, K.T. Seol
    KAERI, Daejon
  Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government.

A 3MeV RFQ upgrade for 100MeV proton accelerator has been fabricated at PEFP (Proton Engineering Frontier Project). The tuning of the cavity was carried out before and after the brazing to meet the condition that the quadrupole field profile is within 1% of design value and dipole component is less than 1% of quadrupole one. The ancillary system such as high power RF including klystron power supply and cooling system were already tested up to operating level. Therefore, the main issues of the tests were cavity conditioning up to full power level and low duty beam test. After the completion of the beam test of RFQ itself, the 20MeV DTL which has been tested independently will be carried out. In this paper, the test results of the PEFP 3MeV RFQ upgrade including high power conditioning and low duty beam acceleration are presented.

FPAE046 Initial Test of the PEFP 20MeV DTL vacuum, proton, alignment, power-supply 2917
  • H.-S. Kim, Y.-S. Cho, S.-H. Han, J.-H. Jang, Y.-H. Kim, H.-J. Kwon, M.-Y. Park, K.T. Seol
    KAERI, Daejon
  • Y.-S. Hwang
    SNU, Seoul
  Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government.

A conventional 20MeV drift tube linac (DTL) for the Proton Engineering Frontier Project (PEFP) has been developed as a low energy section of 100MeV accelerator. The machine consists of four tanks with 152 cells supplied with 900kW RF power from 350MHz klystron through the ridge-loaded waveguide coupler. We assembled the fabricated accelerator components and aligned each part with care. We have also prepared the subsystems for the test of the DTL such as RF power delivery system, high voltage DC power supply, vacuum system, cooling system, measurements and control system and so on. The detailed description of the initial test setup and preliminary test results will be given in this paper.

FPAE047 Test Scheme Setup for the PEFP 20MeV DTL beam-losses, quadrupole, resonance, proton 2965
  • H.-S. Kim, Y.-S. Cho, Y.-H. Kim, H.-J. Kwon, K.T. Seol
    KAERI, Daejon
  • Y.-S. Hwang
    SNU, Seoul
  Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government.

A 100MeV proton accelerator is under development for the Proton Engineering Frontier Project (PEFP). The goal of the first stage of the project is to develop a 20MeV accelerator and the initial test of the 20MeV accelerator will be made. The DTL of 20 MeV accelerator consists of four tanks and will be driven with single klystron, which gives rise to some unique problems with regard to the way of independent resonance control for each tank. Some changes made in the LLRF for reducing phase or amplitude error of cavities affect all of four tanks simultaneously, for which it is not possible to use LLRF for individual control of phase and amplitude of each tank. For independent control of each tank, we are going to use the temperature control of the drift tubes as a frequency tuner. During the initial test of the DTL, the phase of each tank will be synchronized with the first tank phase, and beam based test will be performed as if all of tanks were single unit. The detailed description of the test scheme and the analysis results will be given in this paper.

FPAE063 Enhancements of Machine Reliability and Beam Quality in SPring-8 Linac for Top-Up Injection into Two Storage Rings linac, injection, synchrotron, feedback 3585
  • H. Hanaki, T. Asaka, H. Dewa, T. Kobayashi, A. Mizuno, S. Suzuki, T. Taniuchi, H. Tomizawa, K. Yanagida
    JASRI/SPring-8, Hyogo
  SPring-8 has started its top-up operation from May 2004 in order to feed constant photon fluxes to users. The SPring-8 linac has been improved to realize stable and uninterrupted top-up injection into the SPring-8 storage ring and the NewSUBARU storage ring. The beam energy instability of 0.01% rms had been achieved by the following stabilization: RF amplitude and phase stabilization, synchronization of beam timing and linac's 2856 MHz RF and introduction of an energy compensation system (ECS). Feedback controls of steering magnets compensate long-term variation of beam trajectories at ends of beam transport lines. The presentation will include also recent improvements.  
FPAT046 RF Control System for the DESY VUV-FEL Linac feedback, diagnostics, electron, linac 2899
  • V. Ayvazyan, G.M. Petrosyan, K. Rehlich, S. Simrock, P. Vetrov
    DESY, Hamburg
  In the RF system for the Vacuum Ultraviolet Free Electron Laser (VUV-FEL) Linac each klystron supplies RF power to up to 32 cavities. The superconducting cavities are operated in pulsed mode and high accelerating gradients close to the performance limit. The RF control of the cavity fields to the level of 1·10-4 for amplitude and 0.1 degree for phase however presents a significant technical challenge due to the narrow bandwidth of the cavities which results in high sensitivity to perturbations of the resonance frequency by mechanical vibrations (microphonics) and Lorentz force detuning. A digital RF control system has been developed for the VUV-FEL which will demonstrate the required control performance. Presently the Linac is being commissioned, and this effort provides the first full integrated test in the accelerator, including cryogenics, RF, beam transport, and beam diagnostics. The RF control system design and objectives are discussed and compared to the measured performance during the first stage of the VUV-FEL Linac - TESLA Test Facility. Hardware/software design and operational challenges experienced for RF control are presented.  
FPAT056 RF Control System Upgrade at CAMD diagnostics, impedance, resonance, monitoring 3339
  • V.P. Suller
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • M.G. Fedurin, P. Jines, D.J. Launey
    LSU/CAMD, Baton Rouge, Louisiana
  A description is given of the new control system for the RF system of the CAMD light source. The new design being implemented brings all RF signals into the data acquisition system via a modular, custom made, RF detector and renders the amplitude and tune control loops in the VME computer. On line calculations ensure monitoring of proper operation and display the information to the user in an efficient way. In addition, an advanced load impedance monitoring diagnostic has been implemented, being displayed as a Smith Chart, which is based on the system used at the SRS in Daresbury, England.  
FPAT061 CEBAF Distributed Data Acquisition System linac, beam-losses, electron, controls 3541
  • T.L. Allison, T. Powers
    Jefferson Lab, Newport News, Virginia
  Funding: This work was supported by DOE contract DE-AC05-84ER40150 Modification No. M175, under which the Southeastern Universities Research Association (SURA) operates the Thomas Jefferson National Accelerator Facility.

There are thousands of signals distributed throughout Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF) that are useful for troubleshooting and identifying instabilities. Many of these signals are only available locally or monitored by systems with small bandwidths that cannot identify fast transients. The Distributed Data Acquisition (Dist DAQ) system will sample and record these signals simultaneously at rates up to 40 Msps. Its primary function will be to provide waveform records from signals throughout CEBAF to the Experimental Physics and Industrial Control System (EPICS). The waveforms will be collected after the occurrence of an event trigger. These triggers will be derived from signals such as periodic timers or accelerator faults. The waveform data can then be processed to quickly identify beam transport issues, thus reducing down time and increasing CEBAF performance. The Dist DAQ system will be comprised of multiple standalone chassis distributed throughout CEBAF. They will be interconnected via a fiber optic network to facilitate the global triggering of events. All of the chassis will also be connected directly to the CEBAF Ethernet and run EPICS locally. This allows for more flexibility than the typical configuration of a single board computer and other custom printed circuit boards (PCB) installed in a card cage.


FPAT086 Lucretia: A Matlab-Based Toolbox for the Modeling and Simulation of Single-Pass Electron Beam Transport Systems simulation, lattice, linac, electron 4197
  • P. Tenenbaum
    SLAC, Menlo Park, California
  We report on Lucretia, a new simulation tool for the study of single-pass electron beam transport systems. Lucretia supports a combination of analytic and tracking techniques to model the tuning and operation of bunch compressors, linear accelerators, and beam delivery systems of linear colliders and linac-driven Free Electron Laser (FEL) facilities. Extensive use of Matlab scripting, graphics, and numerical capabilities maximize the flexibility of the system, and emphasis has been placed on representing and preserving the fixed relationships between elements (common girders, power supplies, etc.) which must be respected in the design of tuning algorithms. An overview of the code organization, some simple examples, and plans for future development are discussed.  
FOAA006 Digital Low-Level RF Controls for Future Superconducting Linear Colliders linac, feedback, resonance, collider 515
  • S. Simrock
    DESY, Hamburg
  The requirements for RF Control Systems of Superconducting Linear Colliders are not only defined in terms of the quality of field control but also with respect to operability, availability, and maintainability of the RF System, and the interfaces to other subsystems. The field control of the vector-sum of many cavities driven by one klystron in pulsed mode at high gradients is a challenging task since severe Lorentz force detuning, microphonics and beam induced field errors must be suppressed by several orders of magnitude. This is accomplished by a combination of local and global feedback and feedforward control. Sensors monitor individual cavity probe signals, and forward and reflected wave as well as the beam properties including beam energy and phase while actuators control the incident wave of the klystron and individual cavity resonance frequencies. The operability of a large llrf system requires a high degree of automation while the high availability requires robust algorithms, redundancy, and extremely reliable hardware. The maintenance of the llrf demands sophisticated on-line diagnostics for the llrf subsystems to minimize downtime.