MOPP  —  Poster Session   (23-Jun-08   16:00—18:00)

Paper Title Page
MOPP001 Beam-Based Alignment for the CLIC Decelerator 547
 
  • E. Adli, D. Schulte
    CERN, Geneva
 
  The CLIC Drive Beam decelerator requires the beam to be transported with very small losses. Beam-based alignment is necessary in order to achieve this, and various beam-based alignment schemes have been tested for the decelerator lattice. The decelerator beam has an energy spread of up to 90%, which impacts the performance of the alignment schemes. We have shown that Dispersion-Free-Steering works well for the decelerator lattice. However, because of the transverse focusing approach, modifications of the normal DFS schemes must be applied. Tune-up scenarios for the CLIC decelerator using beam-based alignment are also discussed.  
MOPP002 A Study of Failure Modes in the CLIC Decelerator 550
 
  • E. Adli, D. Schulte, I. Syratchev
    CERN, Geneva
 
  The CLIC Drive Beam decelerator is responsible for producing the RF power for the main linacs, using Power Extraction and Transfer Structures (PETS). To provide uniform power production, the beam must be transported with very small losses. In the paper failure modes for the operation of the decelerator are investigated, and the impact on beam stability, loss level and machine protection issues is presented. Quadrupole failure, PETS inhibition and PETS break down scenarios are being considered.  
MOPP003 Study of Abnormal Vertical Emittance Growth in ATF Extraction Line 553
 
  • M. Alabau, A. Faus-Golfe
    IFIC (CSIC-UV), Valencia
  • M. Alabau, P. Bambade, J. Brossard, G. Le Meur, C. Rimbault, F. Touze
    LAL, Orsay
  • D. Angal-Kalinin, J. K. Jones
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • R. Appleby, A. Scarfe
    UMAN, Manchester
  • S. Kuroda
    KEK, Ibaraki
  • G. R. White, M. Woodley
    SLAC, Menlo Park, California
  • F. Zimmermann
    CERN, Geneva
 
  Since several years, the vertical emittance measured in the Extraction Line (EXT) of the Accelerator Test Facility (ATF) at KEK, that will transport the electron beam from the ATF Damping Ring (DR) to the future ATF2 Final Focus beam line, is significantly larger than the emittance measured in the DR itself, and there are indications that it grows rapidly with increasing beam intensity. This long-standing problem has motivated studies of possible sources of this anomalous emittance growth. One possible contribution is non-linear magnetic fields in the extraction region experienced by the beam while passing off-axis through magnets of the DR during the extraction process. In this paper, simulations of the emittance growth are presented and compared to observations. These simulations include the effects of predicted non-linear field errors in the shared DR magnets and orbit displacements from the reference orbit in the extraction region. Results of recent measurements using closed orbit bumps to probe the relation between the extraction trajectory and the anomalous emittance growth are also presented.  
MOPP005 The 2 mrad Crossing Angle Scheme for the International Linear Collider 556
 
  • R. Appleby
    UMAN, Manchester
  • D. Angal-Kalinin
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • P. Bambade, S. Cavalier, G. Le Meur, F. Touze
    LAL, Orsay
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto
 
  The present baseline configuration of the ILC has a 14 mrad crossing angle between the beams at the interaction point. This allows easier extraction of the beams after collisions, but imposes on the other hand more constraints on the control of the beams prior to colliding them. Moreover, some limitations to physics capabilities arise, in particular because of the degraded very forward electromagnetic detector hermeticity and because calibration procedures for (gaseous) tracking detectors become more complex. To mitigate these problems, alternative configurations with very small crossing angles are studied. A new version of the 2 mrad layout was designed last year, based on simpler concepts and assumptions. The emphasis of this new scheme was to satisfy specifications with as few and feasible magnets as possible, in order to reduce costs. Recent progress designing several of the magnets involved and the particular vacuum chamber needed in the shared part of the beam line is reported.  
MOPP006 Machine Induced Backgrounds for FP420 559
 
  • R. Appleby, K. M. Potter, F. Roncarolo, G. J. Sellers
    UMAN, Manchester
  • I. Azhgirey, I. Baishev, I. L. Kurochkin, V. Talanov
    IHEP Protvino, Protvino, Moscow Region
  • M. Ruspa
    INFN-Torino, Torino
 
  The LHC FP420 collaboration is assessing the feasibility of installing forward proton detectors at 420m from the ATLAS and/or CMS interaction points. Such detectors aim at measuring diffracted protons, which lost less than 2% of their longitudinal momentum. The success of this measurement requires a very good understanding of the charged and neutral particle environment in the detector region in order to avoid the signal being swamped as well as for detector survivability. This background receives contributions from beam-gas interactions, halo particles surviving from the Betatron and momentum cleaning systems and secondary showers produced by particles from the 14TeV collision region striking the beampipe upstream of the FP420 detectors. In this paper, such background sources are reviewed, and the expected background rates calculated.  
MOPP007 Wakefield Calculations - Comparison between Simulations and Experimental Data 562
 
  • A. Bungau, R. J. Barlow
    UMAN, Manchester
 
  In linear colliders the collimator wakefields have a significant effect on emittance growth, beam jitter and background estimates. Each simulation code models the collimator wakefields using a different approach and a discussion of the formalism for incorporating wakefields into the particle tracking code Merlin is included in this paper. Using simple collimator types we present the different predictions for bunch shape effects, and also for the wakefield kicks. These kicks are also compared with experimental results from SLAC End Station A.  
MOPP008 Design of the Photon Collimators for the ILC Positron Helical Undulator 565
 
  • A. Bungau
    UMAN, Manchester
  • I. R. Bailey, J. B. Dainton, K. M. Hock, L. J. Jenner, L. I. Malysheva
    Liverpool University, Science Faculty, Liverpool
  • E. Baynham, T. W. Bradshaw, F. S. Carr, J. Rochford
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • A. J. Brummitt, A. J. Lintern
    STFC/RAL, Chilton, Didcot, Oxon
  • J. A. Clarke, O. B. Malyshev, N. C. Ryder, D. J. Scott
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • N. A. Collomb
    STFC/DL, Daresbury, Warrington, Cheshire
  • A. F. Hartin
    OXFORDphysics, Oxford, Oxon
  • S. Hesselbach, G. A. Moortgat-Pick
    Durham University, Durham
  • L. Zang
    Cockcroft Institute, Warrington, Cheshire
 
  A number of photon collimators are placed inside the helical undulator to protect the cold surfaces of the vacuum vessel from being hit by the photons and thus achieving the baseline pressure requirement. Computer simulations were run in order to determine the energy deposition and instantaneous temperature rise in these collimators and various material candidates were studied. This paper presents the status of the simulation.  
MOPP009 Copper Prototype Measurements of the HOM, LOM and SOM Couplers for the ILC Crab Cavity 568
 
  • G. Burt, P. K. Ambattu, A. C. Dexter
    Cockcroft Institute, Lancaster University, Lancaster
  • L. Bellantoni
    Fermilab, Batavia, Illinois
  • P. Goudket, P. A. McIntosh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • Z. Li, L. Xiao
    SLAC, Menlo Park, California
 
  The ILC Crab Cavity is positioned close to the IP and hence is very sensitive to the wakefields induced by the beam. A set of couplers were designed to couple to and hence damp the spurious modes of the crab cavity. As the crab cavity is a deflecting mode cavity, it operates using a dipole mode and has different damping requirements than an accelerating mode cavity. A separate coupler is required for the monopole modes below the operating frequency of 3.9 GHz, known as the LOMs, the opposite polarization of the operating mode, the SOM, and the modes above the operating frequency, the HOMs. Each of these couplers have been manufactured out of copper and measured attached to an aluminium nine cell prototype of the cavity and their external Q factors were measured. The results were found to agree well with numerical simulations.  
MOPP010 Experimental Studies on Drive Beam Generation in CTF3 571
 
  • R. Corsini, S. Bettoni, S. Doebert, P. K. Skowronski, F. Tecker
    CERN, Geneva
  • C. Biscari, A. Ghigo
    INFN/LNF, Frascati (Roma)
  • Y.-C. Chao
    Jefferson Lab, Newport News, Virginia
 
  The objective of the CLIC Test Facility CTF3, built at CERN by an international collaboration, is to demonstrate the main feasibility issues of the CLIC two-beam technology by 2010. CTF3 consists of a 150 MeV electron linac followed by a 42 m long delay loop, an 84 m combiner ring and a two-beam test area. One key-issue studied in CTF3 is the efficient generation of a very high current drive beam, used in CLIC as the power source for the acceleration of the main beam to multi-TeV energies. The beam current is first doubled in the delay loop and then multiplied again by a factor four in the combiner ring by interleaving bunches using transverse deflecting RF cavities. The combiner ring and the connecting transfer line have been installed and put into operation in 2007. In this paper we give the status of the commissioning, illustrate the beam optics measurements, discuss the main issues and present the results of the combination tests.  
MOPP011 Fast Vertical Beam Instability in the CTF3 Combiner Ring 574
 
  • R. Corsini, D. Schulte, P. K. Skowronski, F. Tecker
    CERN, Geneva
  • D. Alesini, C. Biscari, A. Ghigo
    INFN/LNF, Frascati (Roma)
 
  The CLIC Test Facility CTF3 is being built at CERN by an international collaboration, in order to demonstrate the main feasibility issues of the CLIC two-beam technology by 2010. The facility includes an 84 m combiner ring, which was installed and put into operation in 2007. High-current operation has shown a vertical beam break-up instability, leading to high beam losses over the four turns required for nominal operation of the CTF3 ring. Such instability is most likely due to the vertically polarized transverse mode in the RF deflectors used for beam injection and combination. In this paper we report the experimental data and compare them with simulations. Possible methods to eliminate the instability are also outlined.  
MOPP012 DC Breakdown Experiments for CLIC 577
 
  • A. Descoeudres, S. Calatroni, M. Taborelli
    CERN, Geneva
 
  For the production of the Compact Linear Collider (CLIC) RF structures, a material capable of sustaining high electric field, with a low breakdown rate and showing low damages after breakdowns is needed. A DC breakdown study is underway at CERN in order to test candidate materials and surface preparations, and also to have a better understanding of the breakdown mechanism. The saturated breakdown fields of several metals and alloys have been measured, ranging from 100MV/m for Al to 900MV/m for stainless steel, being around 150MV/m for Cu, CuZr and Glidcop, 300MV/m for W, 400MV/m for Mo, Nb and Cr, 650MV/m for V, and 750MV/m for Ti for example. Titanium shows a strong material displacement after breakdowns, while Cu, Mo and stainless steel are more stable. The conditioning speed of Mo can be significantly improved by removing oxides at the surface with a heat treatment, typically at 875°C for 2 hours. DC breakdown rate measurements have been done with Cu and Mo electrodes, showing similar results as in RF experiments: the breakdown probability seems to exponentially increase with the applied field.  
MOPP013 Coupler Kick for Very Short Bunches and its Compensation 580
 
  • M. Dohlus, I. Zagorodnov
    DESY, Hamburg
  • E. Gjonaj, T. Weiland
    TEMF, Darmstadt
 
  In this contribution we estimate two different effects: the kick due to asymmetry of the external accelerating field (coupler RF kick) and the kick due to electromagnetic field of the bunch scattered by the couplers (coupler wake kick). We take into acoount the cavities and calculate the periodic solution for bunch with an rms width of 300 mkm. The different possibilities for compensation of the kick are considered.  
MOPP015 Continuously Adjustable Permanent Magnet Quadrupole for a Final Focus 583
 
  • T. Sugimoto, M. Ichikawa, Y. Iwashita, M. Yamada
    Kyoto ICR, Uji, Kyoto
  • M. Kumada
    NIRS, Chiba-shi
  • S. Kuroda, T. Tauchi
    KEK, Ibaraki
 
  A permanent magnet quadrupole with continuous strength adjustability has been fabricated. It has a five-ring-singlet structure, which was proposed by R. L.Gluckstern. Its small overall diameter allows an outgoing beamline to pass closeby. Since the permanent magnet pieces do not have any vibration source in themselves, this magnet could be used as a quadrupole in a final focus doublet. Such a quadrupole system is described.  
MOPP016 Collimation Aperture for the Beam Delivery System of the International Linear Collider 586
 
  • F. Jackson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
  The beam delivery sytem (BDS) of the international linear collider (ILC) must provide efficient removal of beam halo particles which would cause unacceptable detector background. The collimation aperture or 'collimation depth' is designed such that synchrotron radiation from the halo emitted in the final doublet passes cleanly through the detector interaction region. The ILC BDS collimation depth for several different detector scenarios is evaluated using a semi-analytical technique.  
MOPP017 A Kicker Driver Exploiting Drift Step Recovery Diodes for the International Linear Collider 589
 
  • F. O. Arntz, M. P.J. Gaudreau, A. Kardo-Sysoev, M. K. Kempkes, A. Krasnykh
    Diversified Technologies, Inc., Bedford, Massachusetts
 
  Diversified Technologies, Inc. (DTI) is developing a driver for a kicker strip-line deflector which inserts and extracts charge bunches to and from the electron and positron damping rings of the International Linear Collider. The kicker driver must drive a 50 Ω terminated TEM deflector blade at 10 kV with 2 ns flat-topped pulses, which according to the ILC pulsing protocol, bursts pulses at a 3 MHz rate within one-millisecond bursts occurring at a 5 Hz rate. The driver must also effectively absorb high-order mode signals emerging from the deflector. In this paper, DTI will describe current progress utilizing a combination of high voltage DSRDs (Drift Step Recovery Diodes) and high voltage MOSFETs. The MOSFET array switch, without the DSRDs, is itself suitable for many accelerator systems with 10 – 100 ns kicker requirements. DTI has designed and demonstrated the key elements of a solid state kicker driver which both meets the ILC requirements, is suitable for a wide range of kicker driver applications. Full scale development and test are exptected to occur in Phase II of this DOE SBIR effort, with a full scale demonstration scheduled in 2009.  
MOPP022 Transatlantic Transport of Fermilab 3.9 GHZ Cryomodule for TTF/FLASH to DESY 592
 
  • M. McGee, V. T. Bocean, J. Grimm, W. Schappert
    Fermilab, Batavia, Illinois
 
  In an exchange of technology agreement, Fermilab built and will deliver a 3.9 GHz (3rd harmonic) cryomodule to DESY to be installed in the TTF/FLASH beamline. This cryomodule delivery will involve a combination of flatbed air ride truck and commercial aircraft transport to Hamburg Germany. A description of the isolation and damping systems that maintain alignment during transport and protect fragile components is provided. Initially, transport and corresponding alignment stability studies were performed in order to assess the risk associated with transatlantic travel of a fully assembled cryomodule. Shock loads were applied to the cryomodule by using a coldmass mockup to prevent subjecting actual critical components (such as the cavities and input couplers) to excessive forces. Accumulative and peak shock loads were applied through over-the-road testing and using a pendulum hammer apparatus, respectively. Finite Element Analysis (FEA) studies were implemented to define location of instrumentation for transport studies and provide modal frequencies and shapes. Shock and vibration measurement results of transport studies and stabilization techniques are discussed.  
MOPP023 Test of Short Period SC Undulator 595
 
  • A. A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
 
  We represent details of design and results of test of 4-m long undulator in cryostat having period 12mm and aperture ~6.35 mm allowing K=1.0. This undulator can be used in ILC positron conversion system as well as insertion device for developing FEL systems.  
MOPP024 Depolarization and Beam-beam Effects at the Linear Collider 598
 
  • G. A. Moortgat-Pick, S. Hesselbach
    Durham University, Durham
  • I. R. Bailey, G. A. Moortgat-Pick, B. J.A. Shepherd
    Cockcroft Institute, Warrington, Cheshire
  • D. P. Barber
    DESY, Hamburg
  • E. Baynham, T. W. Bradshaw, F. S. Carr, J. Rochford
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • A. J. Brummitt, A. J. Lintern
    STFC/RAL, Chilton, Didcot, Oxon
  • A. Bungau
    UMAN, Manchester
  • J. A. Clarke, O. B. Malyshev, N. C. Ryder, D. J. Scott
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • J. B. Dainton, K. M. Hock, L. J. Jenner, L. I. Malysheva, L. Zang
    Liverpool University, Science Faculty, Liverpool
  • A. F. Hartin
    OXFORDphysics, Oxford, Oxon
 
  The clean environment at the interaction point of a lepton linear collider allows high-precision measurements for physics analyses. In order to exploit this potential, precise knowledge about the polarization state of the beams is also required. In this paper we concentrate on depolarization effects caused by the intense beam-beam interaction, which is expected to be the dominant source of depolarization. Higher-order effects, as well as critical analyses of the theoretical assumptions used in the past and theoretical improvements in the derivation of suitable equations, are given. Updates on existing simulation programs are reported. Numerical results for the design of the International Linear Collider (ILC) are discussed.  
MOPP025 Design of the Beam Extraction by Using Strip-line Kicker at KEK-ATF 601
 
  • T. Naito, H. Hayano, K. Kubo, S. Kuroda, T. Okugi, N. Terunuma, J. Urakawa
    KEK, Ibaraki
 
  The developing work of the strip-line kicker system for International linear collider(ILC) is carrying out at KEK*. To confirm the performance of the kicker system, the beam extraction test by using strip-line kicker is in progress at KEK-ATF. The multi-bunch beam, which has 2.8ns bunch spacing in the damping ring, is extracted from the damping ring to the extraction line with 308ns duration. The scheme is the same as the kicker of the ILC. The bump orbit and the auxiliary septum magnet will be used with the kicker to clear the geometrical restriction. The detail of the hardware design and the basic performance of each component are presented in this paper.

*T. Naito et al. Development of the Strip-line Kicker System for ILC Damping Ring, Proceedings of PAC07, Albuquerque, New Mexico, USA, pp2772-2274.

 
MOPP027 Placet Based Start-to-end Simulations of the ILC with Intra-train Fast Feedback System 604
 
  • J. Resta-López, P. Burrows, A. F. Hartin
    JAI, Oxford
  • A. Latina, D. Schulte
    CERN, Geneva
 
  Integrated simulations are important to assess the reliability of the luminosity performance of the future linear colliders. In this paper we present multi-bunch tracking simulation results for the International Linear Collider (ILC) from the start of the LINAC to the interaction point. The tracking along the LINAC and the beam delivery system is done using the code Placet. This code allows us to introduce cavity wakefield effects, element misalignment errors and ground motion. Static beam based alignment of the LINAC are also considered. The luminosity and beam-beam parameters are calculated using the code Guinea-Pig. In the framework of the Feedback On Nano-second Timescales (FONT) project, we describe and simulate an updated fast intra-train feedback system in order to correct for luminosity degradation mainly due to high frequency ground motion.  
MOPP028 Technical Specification for the CLIC Two-Beam Module 607
 
  • G. Riddone, H. Mainaud Durand, D. Schulte, I. Syratchev, W. Wuensch, R. Zennaro
    CERN, Geneva
  • R. Nousiainen
    HIP, University of Helsinki
  • A. Samoshkin
    JINR, Dubna, Moscow Region
 
  The 2-m long CLIC module comprises four decelerating structures and two quadrupoles forming a FODO cell. Each decelerating structure powers two accelerating structures. Some accelerating structures are removed at regular intervals to liberate space for a quadrupole of a FODO lattice. The present layout of the standard and special modules is presented as well as the status of the system integration. The main requirements for the different sub-systems (alignment, supporting, stabilization, cooling and vacuum) are introduced together with the major integration constraints. For the key components the specification on pre-alignment and beam-based alignment tolerances is also recalled as well as their influence on the requirements of other sub-systems. For example the required stable thermal behavior and the tight tolerances of accelerating structure (the requirements for the accelerating structure pre-alignment is 0.014 mm at 1? ) in the CLIC linac largely directly the sizing and integration of the cooling system. The paper also covers the main issues related to the module integration in the tunnel. In the last part, the critical issues and future activities are summarized.  
MOPP029 The First Measurement of Low-loss 9-cell Cavity in a Cryomodule at STF 610
 
  • T. Saeki, M. Akemoto, S. Fukuda, F. Furuta, K. Hara, Y. Higashi, T. Higo, K. Hosoyama, H. Inoue, A. Kabe, H. Katagiri, S. Kazakov, Y. Kojima, H. Matsumoto, T. Matsumoto, S. Michizono, T. Miura, Y. Morozumi, H. Nakai, K. Nakanishi, N. Ohuchi, K. Saito, M. Satoh, T. Takenaka, K. Tsuchiya, H. Yamaoka, Y. Yano
    KEK, Ibaraki
  • T. Kanekiyo
    Hitachi Technologies and Services Co., Ltd., Kandatsu, Tsuchiura
  • J. Y. Zhai
    IHEP Beijing, Beijing
 
  We are constructing Superconducting RF Test Facility (STF) at KEK for the R&D of International Linear Collider (ILC) accelerator. In the beginning of year 2008, we installed one high-gradient Low-Loss (LL) type 9-cell cavity into a cryomodule at STF, where we assembled an input coupler and peripherals with the cavity in a clean room, and the assembled cavity packages were dressed with thermal shields and installed into a cryomodule. At the room-temperature, we performed the processing of capacitive-coupling input-coupler upto the RF power of 250 kW. At the temperature of 4 K, we measured the loaded Q of the cavity and the tuner was tested. At the temperature of 2 K, high-power RF was supplied from a klystron to the cavity and the performance of the cavity packeage was tested. This article presents the results of the first test of the Low-Loss (LL) 9-cell cavity package at 2 K in a cryomodule.  
MOPP030 ATF2 Final Focus Orbit Correction and Tuning Optimisation 613
 
  • A. Scarfe, R. Appleby
    UMAN, Manchester
  • D. Angal-Kalinin, J. K. Jones
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
  ATF2 is an upgrade to the ATF facility at KEK, Japan consisting of a replacement to the current ATF extraction line and the addition of a final focus section. The final focus system has been designed, and is aiming to test, the local chromaticity correction scheme as proposed for future linear colliders. The final focus system focuses the ultra-low emittance beams at the collision point in the linear collider. To provide the required small beam sizes and to maintain the beam sizes to nanometer level requires optimised orbit correction and tuning procedures. In this paper, the optimisation of the orbit correction using a global SVD method is discussed, along with the progress on final focus tuning knob analysis. The tuning algorithms used at ATF2 will provide an important feedback for future linear colliders (including the ILC and CLIC).  
MOPP031 Challenges and Concepts for Design of an Interaction Region with Push-pull Arrangement of Detectors - an Interface Document 616
 
  • A. Seryi, T. W. Markiewicz, M. Oriunno, M. K. Sullivan
    SLAC, Menlo Park, California
  • D. Angal-Kalinin
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • B. Ashmanskas, V. R. Kuchler, N. V. Mokhov
    Fermilab, Batavia, Illinois
  • K. Buesser
    DESY, Hamburg
  • P. Burrows
    OXFORDphysics, Oxford, Oxon
  • A. Enomoto, Y. Sugimoto, T. Tauchi, K. Tsuchiya
    KEK, Ibaraki
  • A. Herve, J. A. Osborne
    CERN, Geneva
  • A. A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  • B. Parker
    BNL, Upton, Long Island, New York
  • T. Sanuki
    Tohoku University, School of Scinece, Sendai
  • J. Weisend
    NSF, Arlington
  • H. Y. Yamamoto
    Tohoku University, Sendai
 
  Two experimental detectors working in a push-pull mode has been considered for the Interaction Region of the International Linear Collider [1]. The push-pull mode of operation sets specific requirements and challenges for many systems of detector and machine, in particular for the IR magnets, for the cryogenics system, for alignment system, for beamline shielding, for detector design and overall integration, and so on. These challenges and the identified conceptual solutions discussed in the paper intend to form a draft of the Interface Document which will be developed further in the nearest future. The authors of the present paper include the organizers and conveners of working groups of the workshop on engineering design of interaction region IRENG07 [2], the leaders of the IR Integration within Global Design Effort Beam Delivery System, and the representatives from each detector concept submitting the Letters Of Intent.  
MOPP034 Large Scale Linac Simulations Using a Globalised Scattering Matrix Approach 619
 
  • I. R.R. Shinton, R. M. Jones
    UMAN, Manchester
 
  A globalised cascaded scattering matrix scheme serves as practical method to simulate the electromagnetic (e.m.) fields in the groups of cavities which constitute the main accelerating structures of a linac. The cascaded scattering matrix technique is a well-proven method which allows realistic fabrication errors to be incorporated in an efficient manner without the necessity to re-mesh the entire geometry. Once the unit cell structures have been determined using a numerical scheme, such as finite element method utilized here, the overall cascaded scattering matrix calculation requires little in the way of computational resources or time and is consequently an efficient means of characterizing the e.m. field. Details of the e.m. field, shunt impedance and trapped modes for large scale linac simulations applied to the baseline and alternate high gradient cavities for the ILC and applications to XFEL are presented.  
MOPP035 ILC Siting in Dubna Region (Russia) and ILC activity in JINR 622
 
  • G. Shirkov, Ju. Boudagov, Yu. N. Denisov, I. N. Meshkov, A. N. Sissakian, G. V. Trubnikov
    JINR, Dubna, Moscow Region
 
  The report presents the development of investigations on ILC siting in the Dubna region and ILC technical activity at JINR. Russia is one of candidates now for ILC hosting in the Dubna region. International intergovernmental status of JINR, stable geological and plain relief conditions comfortable location, well developed infrastructure create powerful advantages of JINR among other possible sites. Shallow layout of tunnels and experimental halls could significantly reduce the cost of conventional facilities and siting. Besides JINR physicists take part in several fields of activity in ILC: works on photo injector prototype, participation in design and construction of cryomodules, laser metrology, etc.  
MOPP036 Dark Current Model for ILC Main Linac 625
 
  • N. Solyak, N. V. Mokhov, G. V. Romanov
    Fermilab, Batavia, Illinois
  • Y. I. Eidelman
    BINP SB RAS, Novosibirsk
  • W. M. Tam
    IUCF, Bloomington, Indiana
 
  In the ILC Main Linac the dark current electrons, generated in SRF cavity can be accelerated to hundreds of MeV before being kicked out by quadrupoles and thus will originate electromagnetic cascade showers in the surrounding materials. Some of the shower secondaries can return back into vacuum and re-accelerated again. The results of simulation of the dark current dynamics and energy deposition along the linac are discussed in paper.  
MOPP037 Alignment of the CLIC BDS 628
 
  • A. Latina, D. Schulte, R. Tomas
    CERN, Geneva
 
  Aligning the CLIC Beam Delivery System faces two major challenges, the tight tolerances for the emittance preservation and its strong non-linear beam dynamics. For these reasons conventional beam-based alignment techniques, like dispersion free steering, are only partially successful and need to be followed by optimization algorithms based on other observables, like beam sizes.  
MOPP038 Optimizing the CLIC Beam Delivery System 631
 
  • R. Tomas
    BNL, Upton, Long Island, New York
  • H.-H. Braun, M. Jorgensen, D. Schulte
    CERN, Geneva
 
  The optimization of the new CLIC Final Focus System (FFS) with L*=3.5m is presented for a collection of CLIC beam parameters. The final performance is computed for the full Beam Delivery System including the new diagnostics section. A comparison to previous designs is also presented.  
MOPP039 Beam-Based Alignment, Tuning and Beam Dynamics Studies for the ATF2 Extraction Line and Final Focus System 634
 
  • G. R. White, S. Molloy, M. Woodley
    SLAC, Menlo Park, California
 
  Using a new extraction line currently under construction, the ATF2 experiment plans to test the novel compact final focus optics design with local chromaticity correction intended for use in future linear colliders. With a 1.3 GeV design beam of 30nm normalised vertical emittance extracted from the ATF damping ring, the primary goal is to achieve a vertical spot-size at the IP waist of 37nm. We discuss our planned strategy for tuning the ATF2 beam to meet the primary goal. Simulation studies have been performed to asses the effectiveness of the strategy, including “static” (installation) errors and dynamical effects (ground-motion, mechanical vibration, ring extraction jitter etc.). We have simulated all steps in the tuning procedure, from initial orbit establishment to final IP spot-size tuning. Through a Monte Carlo study of 100's of simulation seeds we find we can achieve a spot-size within ~10% of the design optics value in at least 75% of cases. We also ran a simulation to study the long-term performance with the use of beam-based feedbacks.  
MOPP042 RF Kick in the ILC Acceleration Structure 637
 
  • V. P. Yakovlev, I. G. Gonin, A. Latina, A. Lunin, K. Ranjan, N. Solyak
    Fermilab, Batavia, Illinois
 
  Detailed results of estimations and simulations for the RF kick caused by input and HOM couplers of the ILC acceleration structure are presented. Results of possible beam emittance dilution caused by RF kick are discussed for the main LINAC acceleration structure, and the RF structures of the ILC bunch compressors BC1 and BC2. Methods of the RF kick reduction are discussed.  
MOPP043 Transverse Wake Field Simulations for the ILC Acceleration Structure 640
 
  • V. P. Yakovlev, A. Lunin, N. Solyak
    Fermilab, Batavia, Illinois
 
  Details of wake potential simulation in the acceleration structure of ILC, including the RF cavities and input/HOM couplers are presented. Transverse wake potential dependence is described versus the bunch length. Beam emittance dilution caused by main and HOM couplers is estimated, followed by a discussion of possible structural modifications allowing a reduction of transverse wake potential.  
MOPP044 Cavity Diagnostic System for the Vertical Test of the STF Baseline 9-cell Cavity at KEK 643
 
  • Y. Yamamoto, H. Hayano, E. Kako, S. Noguchi, M. Satoh, T. Shishido, K. Umemori, K. Watanabe
    KEK, Ibaraki
  • S.-I. Moon
    POSTECH, Pohang, Kyungbuk
  • H. Sakai, K. Shinoe
    ISSP/SRL, Chiba
  • Q. J. Xu
    IHEP Beijing, Beijing
 
  Four 9-cell cavities, which are TESLA-type 9-cell cavities, were developed and tested in KEK for the future ILC project. A simple cavity diagnostic system was introduced to search the heating spot and to detect the x-ray emission. It is composed of the carbon resistors and the PIN photo diodes. They were attached on the equator of the cell, around the HOM couplers and on the end flanges. They were very effective to search the heating spot and to detect the x-ray emission during the vertical tests. All cavities eventually had the heating spot around the equator in the final state of the vertical test. It is conceivable that the quality of the electron beam welding was somewhat poor, when the dumbbells were connected. On this February, a new vertical test facility will be completed in STF (Superconducting RF Test Facility). Six 9-cell cavities will be tested by using the new system for S0 plan, which goal is the higher accelerating gradient for ILC. The new temperature and x-ray mapping system and new DAQ system will be introduced. This paper reports the recent status in the new vertical test facility in KEK-STF.  
MOPP045 Study of the Validity of K. Bane's Formulae for the CLIC Accelerating Structure 646
 
  • R. Zennaro
    CERN, Geneva
 
  The comprehension of short range wake is essential for the design of CLIC. Useful tools are the Karl Bane's formulae which predict the short range wake for periodic 2D symmetry structures. The comparison of 2D computations based on ABCI with predicted results and the study of the range of validity of these formulae are the subjects of this paper. A new fitting of the computational results is proposed for structures with very small aperture. A model for rounded iris structures is also proposed.  
MOPP046 Collimation Optimizations, Capture Efficiency, and Primary-Beam Power Loss in the ILC Positron Source 649
 
  • F. Zhou, Y. Nosochkov, J. Sheppard
    SLAC, Menlo Park, California
  • W. Liu
    ANL, Argonne, Illinois
 
  The ILC positron beam generated from a thin Ti target has a wide energy spread and large transverse divergence. With the collection optics immediately downstream of the target and pre-acceleration to 125 MeV, the collected positron beam still has a long tail of positrons with low energies and large transverse divergence, which will be lost in the rest of the ILC positron source beamline. A collimation system is proposed and optimized for the case of a shielded target with quarter-wave transformation collection optics so that the power loss in the magnets and RF structures is effectively controlled within the acceptable level and in the damping ring (DR) within 640 W, assuming 3× 1010 of the captured positrons per bunch in the DR. In this case, the capture efficiency and DR injection efficiency are 13% and 99.8%, respectively. The lower capture efficiency is expected to result in higher injection efficiency and therefore, a lower power loss in the DR. The capture efficiency for the cases of a shielded target with flux concentrator and 5-T immersed target with flux concentrator is 20% and 30%, respectively, with the collimation system.  
MOPP047 Simulation Studies on the Vertical Emittance Growth at the Existing ATF Extraction Beamline 652
 
  • F. Zhou, J. W. Amann, S. Seletskiy, A. Seryi, C. M. Spencer, M. Woodley
    SLAC, Menlo Park, California
 
  Significant dependence of the vertical emittance growth on the beam intensity was experimentally observed at the Accelerator Test Facility (ATF) at KEK extraction beamline. This technical note describes the simulations of possible vertical emittance growth sources, particularly in the extraction channel, where the magnets are shared by both the ATF extraction beamline and its damping ring. The vertical emittance growth is observed in the simulations by changing the beam orbit in the extraction channel, even with all optics corrections. The possible reasons for the experimentally observed dependence of the vertical emittance growth on the beam intensity are discussed. An experiment to measure the emittance versus beam orbit at the existing ATF extraction beamline is underway*.

*M. Alabau et al. Study of Abnormal Vertical Emittance Growth in ATF Extraction Line, this proceeding.

 
MOPP048 Fast Ion Instability in the CLIC Transfer Line and Main Linac 655
 
  • G. Rumolo, D. Schulte
    CERN, Geneva
 
  The Fast Ion Instability is believed to be a serious danger for bunch trains propagating in the CLIC electron transfer line and main linac, since it may strongly affect the bunches in the tail of the train if the vacuum pressure is not below a certain threshold. We have developed the FASTION code, which can track electrons through a FODO cell line and takes into account their interactions with the produced (and possibly trapped) ions. We describe how this tool can be used for setting tolerances on the vacuum pressure and for giving specifications for the design of a feedback system.  
MOPP049 Collective Effects in the CLIC Damping Rings 658
 
  • G. Rumolo, J. B. Jeanneret, Y. Papaphilippou, D. Quatraro
    CERN, Geneva
 
  The possible performance limitations coming from collective effects in the CLIC damping rings are the subject of this paper. In particular, the consequences of space charge, due to the very high beam brilliance, and of the resistive wall impedance, due to the locally very small beam pipe, are considered potentially dangerous in spite of the high beam energy. Hence, they have been studied in detail with the HEADTAIL code, which has been modified in order to take into account a finer lattice structure as well as multi-bunch effects of the resistive wall wake field. The study aims at setting the intensity thresholds determined by these phenomena.  
MOPP050 Electron Cloud Build Up and Instability in the CLIC Damping Rings 661
 
  • G. Rumolo, Y. Papaphilippou
    CERN, Geneva
  • W. Bruns
    WBFB, Berlin
 
  Electron cloud can be formed in the CLIC positron damping ring and cause intolerable tune shift and beam instability. 2D and 3D build up simulations with the Faktor2 code, developed at CERN, have been done to predict the cloud formation in the arcs and wigglers of the damping rings. HEADTAIL simulations have been used to study the effect of this electron cloud on the beam and assess the thresholds above which the electron cloud instability would set in.  
MOPP051 Effect of Fill Patterns on Extraction Jitter in Damping Rings 664
 
  • K. M. Hock, A. Wolski
    Cockcroft Institute, Warrington, Cheshire
 
  Injection of fresh bunches into a storage ring can induce jitter on stored bunches, as a result of wake field coupling. This transient effect can lead to an undesirable increase in the emittance of stored bunches; in the case of linear collider damping rings, there can also be jitter in the extracted bunches, which can adversely affect performance. We consider how the wake field coupling in a storage ring depends on the fill pattern, and, for the ILC damping rings, present the results of simulations of the transverse dynamics with a resistive wall wake field for a number of different fill patterns. We draw correlations between the extraction jitter and various machine parameters, including the fill pattern.  
MOPP055 A Comparison of Tuning Strategies for a Linear Collider Damping Ring 667
 
  • J. K. Jones
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
  Emittance preservation is an important aspect in the design and running of any new Linear Collider design, with a direct consequence on the luminosity of the machine. Damping rings provide the lower limit on achievable emittance, and so are designed to produce as small a vertical emittance as possible, not only for luminosity considerations, but also to relax tolerances in downstream, emittance diluting, systems. Maintaining such small emittances requires that the damping ring emittance is regularly “tuned”. Several methods of damping ring tuning are investigated, and analysed both in terms of their relative effectiveness, under a variety of conditions, and the non-monetary cost involved in implementing and using the various algorithms.  
MOPP056 Beam Coupling Impedance in the ILC Damping Rings 670
 
  • M. Korostelev, O. B. Malyshev, A. Wolski
    Cockcroft Institute, Warrington, Cheshire
  • A. F. Grant, J. Lucas
    STFC/DL, Daresbury, Warrington, Cheshire
 
  The ILC damping rings have stringent specifications for beam quality and stability. To avoid instabilities, the various components in the vacuum chamber will need to be carefully designed to minimize the longitudinal and transverse wake fields. We present the results of impedance calculations for various components that are expected to make a significant contribution to the overall machine impedance.  
MOPP057 ILC DR Vacuum Design and E-cloud 673
 
  • O. B. Malyshev
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • W. Bruns
    WBFB, Berlin
 
  An electron cloud parameters and vacuum design are tightly bounded to each other. Input parameters for the e-cloud depend on shape of vacuum chamber and surface property (material, roughthness, coatings, etc.), electron multipacting in the vacuum chamber causes the electron stimulated gas desorption and may require modification of vacuum system to deal with it. This paper describes the e-cloud modelling performed in a way to optimise ILC DR vacuum design in positron ring and to have clear understanding what modification in vacuum chamber are required. Three parameters of e-cloud were varied in turn: photo-electron emission, secondary electron yield and gas pressure. It was found all three parameter should not exceed certain value to keep the e-cloud density to an acceptable level. The energy and intensity of electron bombardment of the vacuum chamber walls and electron stimulated gas desorption were also calculated. It was found that electron stimulated gas desorption is comparable or larger than the photon stimulated desorption and should be considered in vacuum design.  
MOPP059 Study for ILC Damping Ring at KEKB 676
 
  • K. Ohmi, J. W. Flanagan, H. Fukuma, K.-I. Kanazawa, H. Koiso, M. Masuzawa, Y. Ohnishi, K. Oide, Y. Suetsugu, M. Tobiyama
    KEK, Ibaraki
  • M. T.F. Pivi
    SLAC, Menlo Park, California
 
  ILC damping ring consists of very low emittance electron and positron storage rings. It is necessary for ILC damping ring to study electron cloud effects in such low emittance positron ring. We propose a low emittance operation of KEKB to study the effects.  
MOPP060 Parameter Scan for the CLIC Damping Rings 679
 
  • Y. Papaphilippou, H.-H. Braun, M. Korostelev
    CERN, Geneva
 
  Triggered by the RF frequency reduction of the CLIC main linac cavities, the damping ring parameters had to be reevaluated and the rings' performance adapted to the new luminosity requirements. In view of a staged approach for reaching the ultimate energy of the collider, the dependence of the rings output emittances under the influence of Intrabeam Scattering is evaluated with respect to different beam characteristics such as bunch population, beam energy, coupling and longitudinal beam characteristics.  
MOPP061 Non Linear Dynamics Study of the CLIC Damping Rings Using Sympletic Integrators 682
 
  • Y. Papaphilippou
    CERN, Geneva
  • Ch. Skokos
    IMCCE, Paris
 
  A class of symplectic integrators with positive steps (SABA2) is applied to investigate the non-linear dynamics of the CLIC damping rings. The detrimental effect of the chromaticity sextupoles is studied using frequency and diffusion maps and verified with MADX ptc dynamic aperture tracking. The reduction of the dynamic aperture for off-momentum particles is also investigated.  
MOPP062 Optics Design Considerations for the CLIC Pre-damping Rings 685
 
  • Y. Papaphilippou
    CERN, Geneva
  • F. Antoniou
    National Technical University of Athens, Zografou
 
  The CLIC pre-damping rings have to accommodate a large emittance beam, coming in particular from the positron source and reduce its size to low enough values for injection into the main damping rings. Linear lattice design options based on an analytical approach for theoretical minimum emittance cells are presented. In particular the parameterisation of the quadrupole strengths and optics functions with respect to the emittance and drift lengths is derived. Complementary considerations regarding constraints imposed by positron stacking and input momentum spread are also considered.  
MOPP063 A New Chicane Experiment in PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders 688
 
  • M. T.F. Pivi, D. Arnett, F. D. Cooper, D. Kharakh, F. King, R. E. Kirby, B. Kuekan, J. J. Lipari, M. Munro, J. S.T. Ng, J. Olszewski, T. O. Raubenheimer, J. Seeman, B. Smith, C. M. Spencer, L. Wang, W. Wittmer
    SLAC, Menlo Park, California
  • C. M. Celata, M. A. Furman
    LBNL, Berkeley, California
 
  Beam instability caused by the electron cloud has been observed in positron and proton storage rings and it is expected to be a limiting factor in the performance of the positron Damping Ring (DR) of future Linear Colliders such as ILC and CLIC. Possible remedies for the electron cloud effect include thin-film coatings, surface conditioning, antechamber, clearing electrodes, and chamber with grooves or slots. The effect is expected to be particularly severe in magnetic field regions. To test this and possible mitigation methods, we have installed a new 4-dipole chicane experiment in the PEP-II Low Energy Ring (LER). We have also installed test chambers in straight field free regions. The associated chamber consists of bare aluminum and TiN-coated inner surface sections. Each section is instrumented with arrays of readout electrodes and retarding grids. Installation of a grooved chamber is also planned. In this paper, we describe the ongoing R&D effort at SLAC to reduce the electron cloud effect in linear colliders. We present the design of the chicane, the chambers and diagnostics, as well as the experimental results obtained.  
MOPP064 Secondary Electron Yield Measurements and Groove Chambers Update Tests in the PEP-II Beam Line 691
 
  • M. T.F. Pivi, F. King, R. E. Kirby, T. W. Markiewicz, T. O. Raubenheimer, J. Seeman, L. Wang
    SLAC, Menlo Park, California
 
  In the Low Energy Ring (LER) of the PEP-II accelerator, we have installed vacuum chambers with rectangular grooves in straight sections to test this possible mitigation technique for the electron cloud effect in the positron damping ring (DR) of the future Linear Colliders such as ILC and CLIC. We have also installed chambers to monitor the secondary electron yield (SEY) of TiN, TiZrV (NEG) and technical accelerator materials under the effect of electron and photon conditioning in situ. Furthermore, we have also installed test chambers in a new 4-magnet chicane. We describe the ongoing R&D effort to mitigate the electron cloud effect in the ILC damping ring, the chambers installation in the PEP-II and latest results.  
MOPP065 Microwave Transmission Measurement of the Electron Cloud Density in the Positron Ring of PEP-II 694
 
  • M. T.F. Pivi, A. Krasnykh
    SLAC, Menlo Park, California
  • J. M. Byrd, S. De Santis, K. G. Sonnad
    LBNL, Berkeley, California
  • F. Caspers, T. Kroyer, F. Roncarolo
    CERN, Geneva
 
  Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of these accelerators, it is difficult to probe the low energy electron clouds over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave which is independently excited and transmitted over a section of the accelerator. We infer the absolute phase shift with relatively high accuracy from the phase modulation of the transmission due to the modulation of the electron cloud density from a gap in the positively charged beam. We have used this technique for the first time to measure the average electron cloud density over a 50 m straight section in the positron ring of the PEP-II collider at the Stanford Linear Accelerator Center. We have also measured the variation of the density by using low field solenoid magnets to control the electrons.  
MOPP066 Recent Experimental Study of Fast Ion Instability in ATF Damping Ring 697
 
  • N. Terunuma, Y. Honda, T. Naito, J. Urakawa
    KEK, Ibaraki
  • Eckhard. Elsen, G. X. Xia
    DESY, Hamburg
 
  The Fast Ion Instability (FII) is one of the very high priorities of the damping ring R&D for the International Linear Collider (ILC). The Accelerator Test Facility (ATF) in KEK can provide an ILC damping ring-like beam. A specific FII study in ATF has been launched to characterize this phenomenon for the ILC damping ring. A new gas inlet system has been installed recently in the ATF damping ring to control the ion effect. After N2 gas injection into the vacuum chamber in south straight section of the ring, FII has been observed for elevated gas pressures. Beam size blow-up and emittance growth for various fill patterns are presented in this paper and attributed to FII. Comparison between experimental data and simulation results are given as well.  
MOPP067 Coupling Correction Simulations for the ILC Damping Rings 700
 
  • K. G. Panagiotidis, A. Wolski
    Cockcroft Institute, Warrington, Cheshire
 
  The ILC damping rings are specified to operate with a vertical emittance of 2 pm. To achieve this challenging goal, an effective diagnostic and correction system will be needed; however, BPMs add impedance to the ring, and diagnostics and correctors add complexity and cost. It is therefore desirable to understand how the final achievable emittance depends on the numbers, locations, and performance of the BPMs and correctors, and to determine the minimum number of these components required. We present the results of simulations for the damping rings, indicating the effectiveness of coupling correction for different design scenarios of the diagnostics and correction systems.  
MOPP068 Simulation Study of Fast Ion Instability in the ILC Damping Ring 703
 
  • G. X. Xia, Eckhard. Elsen
    DESY, Hamburg
 
  The so-called fast ion instability potentially constitutes a performance limitation for the damping ring of the International Linear Collider (ILC). Based on the latest baseline lattice of the ILC damping ring the fast ion instability is simulated using a weak-strong code. Various fill patterns are examined to mitigate the onset of the instability. Feedback mechanisms are explored. The growth time of the fast ion instability is estimated for various vacuum pressures on the basis of the simulated results.  
MOPP069 A Prototype Target Wheel for the ILC Positron Source 706
 
  • I. R. Bailey, L. J. Jenner, C. J. Nelson
    Liverpool University, Science Faculty, Liverpool
  • I. R. Bailey
    Cockcroft Institute, Warrington, Cheshire
  • D. G. Clarke, K. P. Davies, A. Gallagher
    STFC/DL, Daresbury, Warrington, Cheshire
  • J. A. Clarke
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • J. Gronberg, L. B. Hagler, W. T. Piggott
    LLNL, Livermore, California
 
  In this paper we describe the design, construction and commissioning of a prototype based on the positron production target wheel planned for the ILC positron source. The efficiency of the current baseline positron source design for the ILC can be improved if the conversion target is partially immersed in the magnetic field of the capture optics, thereby increasing the overall capture efficiency for positrons by a factor of two or more. However, immersion of the rotating target wheel generates strong eddy currents leading to additional heating and stresses on the wheel. The primary purpose of our prototype, which had been assembled at Daresbury Laboratory, is to investigate the effects of eddy currents induced in a titanium alloy wheel moving with rim speeds up to 100 metres per second in magnetic fields of the order of 1 Tesla.  
MOPP070 Construction of a Full Scale Superconducting Undulator Module for the International Linear Collider Positron Source 709
 
  • J. A. Clarke, O. B. Malyshev, D. J. Scott, B. J.A. Shepherd
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • I. R. Bailey, J. B. Dainton, K. M. Hock, L. J. Jenner, L. I. Malysheva, L. Zang
    Liverpool University, Science Faculty, Liverpool
  • E. Baynham, T. W. Bradshaw, A. J. Brummitt, F. S. Carr, A. J. Lintern, J. Rochford
    STFC/RAL, Chilton, Didcot, Oxon
  • A. Bungau
    UMAN, Manchester
  • N. A. Collomb
    STFC/DL, Daresbury, Warrington, Cheshire
  • A. F. Hartin
    OXFORDphysics, Oxford, Oxon
  • S. Hesselbach, G. A. Moortgat-Pick
    Durham University, Durham
  • Y. Ivanyushenkov
    ANL, Argonne, Illinois
  • N. C. Ryder
    University of Bristol, Bristol
 
  The positron source for the ILC is dependent upon a >200m long undulator to generate a high flux of multi-MeV photons. The undulator system is broken down into a series of 4m cryomodules, which each contain two superconducting helical undulators. Following a dedicated R&D phase and the construction and measurement of a number of short prototypes a full scale cryomodule has now been completed for the first time. This paper reports on the design, manufacture, and test results of this cryomodule.  
MOPP071 Intense Stopping Muon Beams 712
 
  • M. A.C. Cummings, R. J. Abrams, R. P. Johnson, C. Y. Yoshikawa
    Muons, Inc, Batavia
  • C. M. Ankenbrandt, M. A. Martens, D. V. Neuffer, K. Yonehara
    Fermilab, Batavia, Illinois
 
  The study of rare processes using stopping muon beams provides access to new physics that cannot be addressed at energy frontier machines. The flux of muons into a small stopping target is limited by the kinematics of the production process and by stochastic processes in the material used to slow the particles. Innovative muon beam cooling techniques are being applied to the design of stopping muon beams in order to increase the event rates in such experiments. Such intense stopping beams will also aid the development of applications such as muon spin resonance and muon-catalyzed fusion.  
MOPP072 A Study of Mechanical and Magnetic Issues for a Prototype Positron Source Target 715
 
  • L. J. Jenner, I. R. Bailey
    Cockcroft Institute, Warrington, Cheshire
  • D. G. Clarke, K. P. Davies, A. Gallagher
    STFC/DL, Daresbury, Warrington, Cheshire
  • J. A. Clarke
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • J. Gronberg, L. B. Hagler, W. T. Piggott
    LLNL, Livermore, California
  • S. Hesselbach
    Durham University, Durham
  • C. J. Nelson
    STFC/RAL, Chilton, Didcot, Oxon
  • J. Rochford
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
 
  In order to construct a high yield, positron source that can meet the intensity requirements of future facilities, a robust conversion target is needed. One solution is to use a rotating titanium alloy wheel upon which a beam of photons is incident. The efficiency of capturing the resulting positrons can be optimised by immersing this system in a magnetic field. As described elsewhere*, a prototype of such a target has been built at Daresbury Laboratory, to investigate the mechanical challenges associated with its construction and to study the magnetic effects that the wheel will experience. In this paper, calibration of the instrumentation, the data acquisition system and the initial results from operating the wheel in a strong magnetic field are described. Such phenomena as the eddy current heating experienced by the wheel are measured and compared to results from modelling codes. Vibrational issues surrounding the wheel and supporting structure at various speeds are studied.

*ID: 3894 A Prototype Target Wheel for the ILC Positron Source

 
MOPP073 Plasma Lens for Muon and Neutrino Beams 718
 
  • S. A. Kahn, S. Korenev
    Muons, Inc, Batavia
  • M. B. Bishai, M. Diwan, J. C. Gallardo, A. Hershcovitch, B. M. Johnson
    BNL, Upton, Long Island, New York
 
  The plasma lens is examined as an alternate to focusing horns and solenoids for use in a neutrino or muon beam facility. The plasma lens concept is based on a combined high current lens/target configuration. The current is fed at electrodes located upstream and downstream form the target where pion capturing is needed. The current flows primarily in the plasma, which has a lower resistivity than the target. A second plasma lens section, with an additional current feed, follows the target to provide shaping of the plasma for optimum focusing. The plasma lens is immersed in an additional solenoidal magnetic field to facilitate the plasma stability. The geometry of the plasma is shaped to provide optimal pion capture. Simulations of this plasma lens system have shown a 25% higher neutrino production than the horn system. Plasma lenses have additional advantages: larger axial currents than horns, minimal neutrino contamination during antineutrino running, and negligible pion absorption or scattering. Results from particle simulations using plasma lens will be presented.  
MOPP074 Improvement of an S-band RF-gun cavity with a Cs-Te Photo-cathode 721
 
  • A. Murata, Y. Hama, T. Hirose, Y. Kato, K. Sakaue, T. Suzuki, M. Washio
    RISE, Tokyo
  • H. Hayano, N. Kudoh, T. T. Takatomi, N. Terunuma, J. Urakawa
    KEK, Ibaraki
  • Y. Kamiya
    University of Tokyo, Tokyo
  • S. Kashiwagi
    ISIR, Osaka
  • M. Kuriki
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima
  • R. Kuroda
    AIST, Tsukuba, Ibaraki
 
  A 1.6cell S-band photo-cathode RF-Gun is one of the good alternatives of the short pulse electron source. Therefore,we are operating as a high brightness short pulse electron source for studying a reaction of radiation chemistry,an inverse Compton scattering at Waseda University and as an injector at KEK-ATF. To improve an electron beam quality and to reduce a dark current,we decided to improve the RF-Gun cavity. Frequency tuning of the half cell of existing RF-gun was performed by the torque control of Helicoflex seal on the cathode plate and two moving rod type tuners were installed on the full cell. Newly designed RF-Gun cavity has four compact tuners on each cell,which can be tune the frequency to deform the cavity wall,to remove the Helicoflex seal and tuning holes that were considered to be the major cause of electric discharge and/or a dark current source. According to these improvements,the Q-value and shunt impedance of the cavity is 30% larger than that of existing guns. As the result,the reduction of dark current is succeeded and the beam energy is reached up to 5.5MeV at 10MW RF input. The detailed results of electron beam generation will be reported at the conference.  
MOPP075 Experimental Generation and Characterization of Uniformly Filled Ellipsoidal Electron Beam Distributions 724
 
  • P. Musumeci, J. Moody, J. B. Rosenzweig, C. M. Scoby
    UCLA, Los Angeles, California
 
  For forty years, uniformly filled ellipsoidal beam distributions have been studied theoretically, as they have had the promise of generating self-fields that produce forces linear in the coordinate offset in all three directions. More recently, a scheme for producing such distributions, which depends on the strong longitudinal expansion of an initially very short beam under its own space charge forces, has been proposed. Here we present the experimental demonstration of this scheme, obtained by illuminating the cathode in an rf photogun with an ultra-short laser pulse (~35 fs rms) with an appropriate transverse profile. The resulting 4 MeV beam spatiotemporal (x,t) distribution is imaged using an rf deflecting cavity with 50 fsec resolution. A temporal asymmetry in the ellipsoidal profile, due to image charge effects at the photocathode, is observed at higher charge operation. This distortion is also found to degrade the transverse beam quality.  
MOPP076 L-Band RF Gun with a Thermionic Cathode 727
 
  • S. Nagaitsev, R. Andrews, M. Church, A. Lunin, O. A. Nezhevenko, N. Solyak, D. Sun, V. P. Yakovlev
    Fermilab, Batavia, Illinois
 
  In this talk we present a design for an L-band (1.3 GHz) rf gun with a two-grid thermionic cathode assembly. The rf gun is design to provide a 10-mA average beam current for 1ms at 5 Hz. These parameters match the requirements of both the ILC and Fermilab Project X test facilities. In our simulations we are able to attain the bunch length at 20-30 degrees (FW), while the output energy can vary 2-4 MeV. We will present the results of our simulations as well as preliminary designs.  
MOPP078 Femtosecond Photocathode Electron Source 730
 
  • J. Yang, K. Kan, T. Kondoh, K. Tanimura, Y. Yoshida
    ISIR, Osaka
  • J. Urakawa
    KEK, Ibaraki
 
  A photocathode-based low-emittance femtosecond-bunch electron source is developed to reveal the hidden dynamics of intricate molecular and atomic processes in materials through experimentation such as time-resolved pulse radiolysis or time-resolved electron diffraction. The transverse and longitudinal dynamics of femtosecond electron beam in a photocathode rf gun were studied. The growths of the emittance, bunch length and energy spread due to the rf and the space charge effects in the rf gun were investigated by changing the laser injection phase, the laser pulse width and the bunch charge. The beam simulation indicates that a sub-100-fs MeV electron source with the normalized transverse emittance of 0.1 mm-mrad and the relative energy spread of 10-4 at bunch charge of 0.1-1pC is achievable in the photocathode rf gun driven by a femtosecond laser light.  
MOPP079 Studies on the Role of a Photon Collimator for the ILC Positron Source 733
 
  • L. Zang
    Cockcroft Institute, Warrington, Cheshire
  • I. R. Bailey, A. Wolski, L. Zang
    Liverpool University, Science Faculty, Liverpool
 
  Use of a helical undulator in the ILC positron source provides the possibility of producing a polarised positron beam. The degree of polarisation of the positrons depends upon the polarisation of the photons produced from the undulator, where the polarisation depends on the photon energy and production angle. We calculate these quantities for one design of the helical undulator for the ILC, investigate approximations commonly made in calculating the undulator photon spectrum and explore the role of of a photon collimator in determining the positron polarisation.  
MOPP080 Studies of Breakdown in a Pressurized RF Cavity 736
 
  • M. BastaniNejad, A. A. Elmustafa
    Old Dominion University, Norfolk, Virginia
  • M. Alsharo'a, P. M. Hanlet, R. P. Johnson, S. Korenev, M. Kuchnir, D. J. Newsham, R. Sah
    Muons, Inc, Batavia
  • C. M. Ankenbrandt, A. Moretti, M. Popovic, K. Yonehara
    Fermilab, Batavia, Illinois
  • D. M. Kaplan
    Illinois Institute of Technology, Chicago, Illinois
  • D. Li
    LBNL, Berkeley, California
  • D. Rose, C. H. Thoma, D. R. Welch
    Voss Scientific, Albuquerque, New Mexico
 
  Previous studies of RF breakdown in a cavity pressurized with dense hydrogen gas have indicated that breakdown probability is proportional to a high power of the surface electromagnetic field. This behavior is similar to the Fowler-Nordheim description of electron emission from a cold cathode, and it implies that breakdown is a quantum mechanical effect that is characterized by the work function of the cavity metal. We describe our present efforts to measure the distributions of work functions at the nanoscale level on the surfaces of the electrodes used in breakdown studies, and to understand how the RF conditioning process affects them.  
MOPP081 Engineering Design of a PETS Tank Prototype for CTF3 Test Beam Line 739
 
  • D. Carrillo, L. García-Tabarés, J. L. Gutierrez, I. Rodriguez, E. Rodríguez García, S. Sanz, F. Toral
    CIEMAT, Madrid
  • G. Arnau-Izquierdo, N. C. Chritin, S. Doebert, G. Riddone, I. Syratchev, M. Taborelli
    CERN, Geneva
  • J. Calero
    CEDEX, Madrid
 
  In the CLIC concept, PETS (Power Extraction and Transfer Structure) role is to decelerate the drive beam and transfer RF power to the main beam. One of the CTF3 test beam line (TBL) aims is to study the decelerated beam stability and evaluate PETS performance. The PETS core is made of eight 800 mm long copper rods, with very tight tolerances for shape (± 20 micron), roughness (less than 0.4 micron) and alignment (± 0.1 mm). Indeed, they are the most challenging components of the tank. This paper reports about the methods of fabrication and control quality of these bars. A special test bench has been designed and manufactured to check the rod geometry by measuring the RF fields with an electric probe. Other parts of the PETS tank are the power extractor, the waveguides and the vacuum tank itself. Industry is partially involved in the prototype development, as the series production consists of 15 additional units, and some concepts could be even applicable to series production of CLIC modules  
MOPP083 Status of High Power Tests of Normal Conducting Single-cell Structures 742
 
  • V. A. Dolgashev, S. G. Tantawi
    SLAC, Menlo Park, California
  • Y. Higashi, T. Higo
    KEK, Ibaraki
 
  We report results of ongoing high power tests of single cell traveling wave and standing wave structures. These tests are part of an experimental and theoretical study of rf breakdown in normal conducting structures at 11.4 GHz*. The goal of this study is to determine the gradient potential of normal-conducting, rf powered particle beam accelerators. The test setup consists of reusable mode launchers and short test structures and powered by SLAC’s XL-4 klystron. The mode launchers and structures were manufactured at SLAC and KEK and tested in SLAC klystron test laboratory.

*V. A. Dolgashev, S. G. Tantawi, et al. “High Power Tests of Normal Conducting Single Cell Structures,” SLAC-PUB-12956, PAC07, Albuquerque, New Mexico, 25-29 June 2007, pp 2430-2432.

 
MOPP084 Installation and Commissioning of the RF System for the New Elettra Booster 745
 
  • A. Fabris, M. Bocciai, L. Bortolossi, M. Ottobretti, C. Pasotti, M. Rinaldi
    ELETTRA, Basovizza, Trieste
 
  The commissioning of the new booster of the Elettra synchrotron radiation source started in Fall 2007. The RF system of the booster is made of a five cells accelerating cavity fed by a 60 kW 500 MHz power plant. The accelerating cavity voltage is ramped along with the booster energy at a 3 Hz repetition rate. The cavity field is controlled by analog feedback loops on amplitude, phase and the resonant frequency. This paper describes the setting into operation of the system and its performances during the commissioning phase of the machine.  
MOPP085 Bench Characterization of a Prototype of a 3rd Harmonic Cavity for the LNLS Electron Storage Ring 748
 
  • R. H.A. Farias, D. A. Nascimento, C. Pardine, P. F. Tavares
    LNLS, Campinas
 
  The UVX electron storage ring at the Brazilian Synchrotron Light Laboratory suffers from longitudinal instabilities driven by a HOM of one of the RF cavities. The operational difficulties related to these unstable modes were successfully overcome by determining the proper cavity temperature set point in combination with phase modulation of the RF fields at the second harmonic of the synchrotron frequency. However, a serious drawback of the method is to increase the energy spread of the electron beam, which is detrimental for the undulator emission spectrum. The use of higher harmonic cavities is a more appropriate technique since it provides damping of the longitudinal modes without increasing the energy spread. A full scale prototype of a 3rd harmonic cavity was manufactured at the LNLS workshops and had its main rf properties measured. Special care was taken to measure the shunt impedance of the fundamental resonant mode since it determines how many cavities will be necessary for the adequate operation of the system, which is designed to operate in passive mode. In this work we present the results of the bench characterization of the cavity.  
MOPP086 A Novel Fabrication Technique for the Production of RF Photoinjectors 751
 
  • P. Frigola, R. B. Agustsson, S. Boucher, A. Y. Murokh
    RadiaBeam, Los Angeles
  • D. Cormier, T. Mahale
    NCSU, Raleigh
  • L. Faillace
    Rome University La Sapienza, Roma
  • J. B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
 
  Recent developments in Direct Metal Free Form Fabrication (DMFFF) technology may make it possible to design and produce near netshape copper structures for the next generation of very high duty factor, high gradient radio frequency (RF) photoinjectors. RF and thermal-management optimized geometries could be fully realized without the usual constraints and compromises of conventional machining techniques. A photoinjector design incorporating DMFFF and results from an initial material feasibility study will be reported.  
MOPP087 RF System for the SSRF Booster Synchrotron 754
 
  • Q. Gu, L. X. Chen, M. Chen, L. Feng, Z. Q. Feng, H. T. Hou, J. F. Liu, C. Luo, D. Q. Mao, F. Wang, Zh. G. Zhang, S. J. Zhao, Y. B. Zhao, Z. S. Zhou
    SINAP, Shanghai
 
  The booster synchrotron of the Shanghai Synchrotron Radiation Facility (SSRF) ramps the energy of electron beam from 150 MeV to 3.5 GeV with a repetition rate of 2 Hz. The guidelines of the system design are simplicity and reliability, and the ability of top-up injection for the storage ring is also taking into account. The RF system consists of a 180kW CW plant with a WR1800 waveguide line, two PETRA type 5-cell cavities and an analog low level RF electronics with vector-sum scheme. An overview, installation and commissioning of the whole booster RF system are presented in this paper. The performance of the RF system with the beam is also given.  
MOPP088 The High Harmonics Cavity System for the New Experimental Storage Ring at FAIR 757
 
  • R. G. Heine, C. Dimopoulou, U. Laier
    GSI, Darmstadt
 
  The "Facility for Antiproton and Ion Research" (FAIR) will consist of several synchrotrons and storage rings dedicated to target experiments as well as in-situ experiments. One of the in-situ experiments is ELISe, a head-on collision of a heavy ion beam in the new experimental storage ring(NESR) with an electron beam prepared in the electron ring (ER). The vertex is placed in a bypass to the NESR where both rings have a common straight section. To prepare the heavy ion beam for collision with the bunched electron beam circulating at a fixed repetition rate a dedicated RF system called high harmonics cavity system (HHC) operating at a frequency of 44.7MHz is needed. The HHC will be realised as a disk loaded coaxial quarter wave resonator. This paper deals with the actual development status of this RF system, including analytically derived voltage demands, multipactor thresholds and considerations on input coupling and HOM damping.  
MOPP090 Incorporating RF into a Muon Helical Cooling Channel 760
 
  • S. A. Kahn, M. Alsharo'a, R. P. Johnson
    Muons, Inc, Batavia
  • D. R. Broemmelsiek, A. Jansson, V. Kashikhin, V. S. Kashikhin, A. L. Klebaner, G. F. Kuznetsov, G. V. Romanov, A. V. Shemyakin, D. Sun, K. Yonehara, A. V. Zlobin
    Fermilab, Batavia, Illinois
  • L. Thorndahl
    CERN, Geneva
 
  A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides solenoidal, helical dipole and helical quadrupole fields has shown considerable promise in providing six-dimensional cooling for muon beams. The energy lost by muons traversing the gas absorber needs to be replaced by inserting RF cavities into the lattice. Replacing the substantial muon energy losses using RF cavities with reasonable gradients will require a significant fraction of the channel length be devoted to RF. However, to provide the maximum phase space cooling and minimal muon losses, the helical channel should have a short period and length. In this paper we shall examine three approaches to include RF cavities into the HCC lattice:
  1. Use higher frequency cavities that can be placed inside the magnetic channel,
  2. Interleave cavities between magnetic coil rings, and
  3. Place banks of RF cavities between segments of HCC channels.
Each of these approaches has positive and negative features that need to be evaluated in selecting the proper concept for including RF into the HCC system.
 
MOPP091 Upgrade of Input Power Coupling System for the SNS RFQ 763
 
  • Y. W. Kang, A. V. Aleksandrov, P. E. Gibson, T. W. Hardek, C. Luck, R. C. Peglow, A. V. Vassioutchenko
    ORNL, Oak Ridge, Tennessee
 
  A RF input power coupler system has been developed for upgrade of input coupling to the RFQ in the SNS linac front-end. The design employs two coaxial loop couplers for 402.5 MHz operation. Two couplers are used in parallel to power the accelerating structure with up to 800 kW total peak power at 8% duty cycle. Each coupler loop has a coaxial ceramic window that is connected to each output of a magic-T waveguide hybrid splitter through a coaxial to waveguide transition. The coaxial loop couplers have been designed, manufactured, and high power processed. This paper presents the following: RF and mechanical designs of the couplers and system, procedure and result of high power RF conditioning, and test and operation results of the upgraded system.  
MOPP092 Efficient Fan-out RF Vector Control Algorithm 766
 
  • Y. W. Kang
    ORNL, Oak Ridge, Tennessee
 
  A new RF vector control algorithm for fan-out power distribution using reactive transmission line circuit parameters for maximum power efficiency is presented. This control with fan-out power distribution system is considered valuable for large scale SRF accelerator systems to reduce construction costs and save on operating costs. Other fixed power splitting systems with individual cavity voltage control at each cavity input may not deliver the power efficiency since excessive power needs to be maintained at each cavity input. In a fan-out RF power distribution system, feeding multiple accelerating cavities with a single RF power generator can be accomplished by adjusting phase delays between the load cavities and reactive loads at the cavity inputs for independent control of cavity RF voltage vectors. In this approach, the RF control parameters for a set of specified cavity RF voltage vectors is determined for a whole fan-out system. The reactive loads and phase shifts can be realized using high power RF phase shifters.  
MOPP093 Fast L-band Waveguide Phase Shifter 769
 
  • S. Kazakov, S. V. Shchelkunov
    Omega-P, Inc., New Haven, Connecticut
  • J. L. Hirshfield
    Yale University, Physics Department, New Haven, CT
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • E. Nenasheva
    Ceramics Ltd., St. Petersburg
  • V. P. Yakovlev
    Fermilab, Batavia, Illinois
 
  During the operation of accelerators it is often important to rapidly change the parameters of the RF system, such as cavity resonant frequency, coupling, or electrical length. For this purpose a fast L-band planar phase shifter has been designed, that has advantages compared to the coaxial scheme considered before by the authors (EPAC 06). The phase shifter is based on a new ferroelectric ceramic, whose permittivity changes with application of an external voltage. The switching time depends on only the external HV circuit and can by less than a few microseconds. The conceptual design and electrical parameters of the new phase shifter are presented, as are first results of low power measurements on a 1/3 model.  
MOPP094 Reduction of Q-loss-effects in Ferrite-loaded Cavities 772
 
  • H. G. Koenig, S. Schaefer
    GSI, Darmstadt
 
  Accelerating cavities loaded with Ni-Zn ferrites have been widely used in synchrotrons for many years. So far their performance is significantly limited by the so-called high-loss-effect (HLE) or quality-loss-effect (QLE). After some milliseconds, this effect leads to a sudden drop of the resonator's voltage namely under the following conditions: fixed frequencies with RF-power above a specific threshold level and a parallel DC-biasing. The mechanism of this unwanted loss has not been fully understood yet. Now a simple method has been found to work against this effect with the aid of mechanical damping of surface waves. For small samples of ferrites the QLE is fully suppressed by using a rubber belt around the circumference or by covering the surface with a thin layer of hot-melt adhesive. We were able to show that similar methods applied to full size rings lead to a significant increase of the onset voltage of the QLE. Most of the existing ferrite loaded accelerating cavities with QLE-limitations can be increased in their accelerating voltage by the above-mentioned modification.  
MOPP095 Advanced Experimental Techniques for RF and DC Breakdown Research 775
 
  • J. W. Kovermann
    RWTH, Aachen
  • S. Calatroni, A. Descoeudres, T. Lefevre, W. Wuensch
    CERN, Geneva
 
  Advanced experimental techniques are being developed to do in-situ analysis of DC and RF breakdowns. First measurements with a specially built spectrometer have been made with a DC spark setup at CERN and with CLIC accelerating structures in the 30GHz power test facility. This spectrometer measures the light intensity development during a breakdown for narrow wavelength intervals in the visible and near infrared range which will give information about the involved elements, temperature and plasma parameters and eventually precursors of a breakdown. Planned experiments for X-ray spectroscopy and imaging, measurements of RF-signals and ion and electron energy distribution and infrared imaging of breakdown sites are presented.  
MOPP096 C-band Linac Optimization for a Race-track Microtron 778
 
  • Yu. A. Kubyshin
    UPC, Barcelona
  • D. Carrillo, L. García-Tabarés, F. Toral
    CIEMAT, Madrid
  • A. V. Poseryaev, V. I. Shvedunov
    MSU, Moscow
 
  Optimization results of a C-band standing wave on-axis coupled linac for a miniature race-track microtron (RTM) are presented. The optimization procedure includes three steps: choice of the linac cells lengths and field strength following requirements of the RTM beam dynamics, 2D cells geometry optimization to maximize the shunt impedance and minimize the surface field strength and, finally, full scale 3D optimization. The 3D calculations were done independently with two codes: ANSYS and HFSS. Various methods of calculation of the coupling slots dimensions, including the waveguide-linac coupling slot, are described in detail.  
MOPP097 Measurements on the Rf Cavity for the ALBA Storage Ring 781
 
  • M. L. Langlois, M. Cornelis, F. Pérez, P. Sanchez
    ALBA, Bellaterra
 
  ALBA storage ring will use 6 ambient temperature nose cone HOM damped cavities tuned at 500 MHz, designed at BESSY and known as the EU cavity. A first one, manufactured by ACCEL, was delivered in 2007 to investigate on its behaviour. This paper describes the data collected during investigation. First, bead-pull measurements were performed to assess impedance, both on fundamental and high order modes. Emphasis was put on E011, due to the discrepancy between expected values and results for this mode. The vacuum bake-out and related pressure are shown. Then, the cavity was conditioned and observations were made on multipacting levels, conditioning time and surface temperatures. The latter were found inhomogeneous and leads are detailed to avoid local overheating.  
MOPP098 A 201-MHz Normal Conducting RF Cavity for the International MICE Experiment 784
 
  • D. Li, A. J. DeMello, S. P. Virostek, M. S. Zisman
    LBNL, Berkeley, California
  • R. A. Rimmer
    Jefferson Lab, Newport News, Virginia
 
  MICE is a demonstration experiment for the ionization cooling of muon beams. Eight RF cavities are proposed to be used in the MICE cooling channel. These cavities will be operated in a strong magnetic field; therefore, they must be normal conducting. The cavity design and construction are based on the successful experience and techniques developed for a 201-MHz prototype cavity for the US MUCOOL program. Taking advantage of a muon beam’s penetration property, the cavity employs a pair of curved thin beryllium windows to terminate conventional beam irises and achieve higher cavity shunt impedance. The cavity resembles a round, closed pillbox cavity. Two half-shells spun from copper sheets are joined by e-beam welding to form the cavity body. There are four ports on the cavity equator for RF couplers, vacuum pumping and field probes. The ports are formed by means of an extruding technique.  
MOPP099 MICE RF System 787
 
  • A. J. Moss, P. A. Corlett, J. F. Orrett, J. H.P. Rogers
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
  The Muon Ionisation Cooling Experiment (MICE) at the Rutherford Appleton Laboratory uses normal conducting copper cavities to re-accelerate a muon beam after it has been retarded by liquid hydrogen absorbers. Each cavity operates at 200MHz and requires 1MW of RF power in a 1ms pulse at a repetition rate of 1Hz. In order to provide this power, a Thales TH116 triode, driven by a Burle 4616 tetrode is used, with each amplifier chain providing ~2.5MW. This power is then split between 2 cavities. The complete MICE RF system is described, including details of the low level RF, the power amplifiers and the coaxial power distribution system.  
MOPP100 Performance of Compact Electron Injector on Evanescent Oscillations 790
 
  • V. V. Mytrochenko, M. I. Ayzatskiy, I. V. Khodak, K. Kramarenko, V. A. Kushnir, A. Opanasenko, S. A. Perezhogin, D. L. Stepin, Z. V. Zhiglo
    NSC/KIPT, Kharkov
 
  An injector on the basis of a resonator structure with exponentially increasing amplitude of the electric field along an axis was developed at NSC KIPT. The injector is supplied with RF power through a rectangular-to-coaxial waveguide transition to provide axial symmetry of the accelerating field. The injector was designed to provide the output current up to 1 A at particle energy up to 1 MeV. Results of the injector test are presented in the work. Results obtained are compared with calculated ones.  
MOPP102 High Field Gradient RF System for a Spiral FFAG, RACCAM 793
 
  • C. Ohmori
    KEK, Ibaraki
  • J. Fourrier, J. Pasternak
    LPSC, Grenoble
  • F. Meot
    CEA, Gif-sur-Yvette
 
  A high field-gradient RF system for a spiral FFAG is described. It is wideband to cover the frequency of 3 to 7.5 MHz. The beam will be accelerated with a high repletion rate of 100 Hz to fit requirements for hadron therapy. The cavity has a wide aperture of 90 cm in horizontal direction to allow a large excursion for beam acceleration. It has less than 40 cm in length to fit a very short straight section.  
MOPP103 High Field Gradient RF System for Bunch Rotation in PRISM-FFAG 796
 
  • C. Ohmori
    KEK, Ibaraki
  • M. Aoki, Y. Arimoto, I. Itahashi, Y. Kuno, Y. Kuriyama, A. Sato, M. Y. Yoshida
    Osaka University, Osaka
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto
  • Y. Mori
    KURRI, Osaka
 
  The PRISM project aims to supply a high quality muon beam using a wide aperture FFAG for mu-e conversion experiment. The low energy muon which has a large momentum spread will be manipulated in the FFAG using a bunch rotation technique with a low frequency RF around 3.5 MHz. Because of a short lifetime of muon, the rotation should be end in 5-6 turns in the FFAG and more than 2 MV is needed. The low frequency RF system using a magnetic alloy is designed to achieve a very high field gradient of more than 200 kV/m. The whole system is designed for a very low duty pulse operation to minimize the cost. The system has been modified to operate at 2 MHz for the beam test using alpha particle. A field gradient of more than 100 kV/m has been obtained by the preliminary test.  
MOPP104 Possible Upgrade Scenario for J-PARC Ring RF 799
 
  • C. Ohmori, K. Hara, A. Takagi, M. Toda, M. Yoshii
    KEK, Ibaraki
  • K. Hasegawa, M. Nomura, A. Schnase, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
  The whole J-PARC RCS RF system is operational and during beam commissioning in 2007 the beam in RCS was successfully accelerated to final energy and then extracted. The Main Ring RF system has been installed in the tunnel. Both Ring RF systems are based on the new technology using magnetic alloy loaded cavities and have achieved higher field gradient than existing ferrite base RF systems in this frequency region. For the future upgrade of the J-PARC Main Ring, a short accelerating cycle is required to increase the average beam current. In this paper, a possible upgrade scenario for RF cavities based on improvements of the magnetic alloy ring cores will be described.  
MOPP105 Compact, Tunable RF Cavities 802
 
  • M. Popovic, C. M. Ankenbrandt, E. Griffin, A. Moretti, R. E. Tomlin
    Fermilab, Batavia, Illinois
  • M. Alsharo'a, I. B. Enchevich, R. P. Johnson, S. Korenev
    Muons, Inc, Batavia
 
  New developments in the design of fixed-field alternating gradient (FFAG) synchrotrons have sparked interest in their use as rapid-cycling, high intensity accelerators of ions, protons, muons, and electrons. Potential applications include proton drivers for neutron or muon production, rapid muon accelerators, electron accelerators for synchrotron light sources, and medical accelerators of protons and light ions for cancer therapy. Compact RF cavities that tune rapidly over various frequency ranges are needed to provide the acceleration in FFAG lattices. An innovative design of a compact RF cavity that uses orthogonally biased ferrite for fast frequency tuning and liquid dielectric to adjust the frequency range is being developed using physical prototypes and computer models.  
MOPP106 Study of Radiation From RF Cavities 805
 
  • R. Sandstrom
    DPNC, Genève
  • D. Huang
    IIT, Chicago, Illinois
  • J. Norem
    ANL, Argonne, Illinois
 
  Essential for muon accelerators such as neutrino factories or muon colliders, ionization cooling channels use RF cavities to restore the energy lost in liquid hydrogen absorbers. One major limitation in cooling comes from electrons emitted from the cavities which can cause breakdowns or unacceptable thermal load to the liquid hydrogen vessels. In the Muon Ionization Cooling Experiment MICE, these electrons also cause background in the detectors. This paper presents simulations related to these dark currents, and analysis of data from a direct measurement of this radiation in the MuCool Test Area (MTA).  
MOPP108 Status of HOM Damped Room-temperature Cavities for the ESRF Storage Ring 808
 
  • V. Serriere, A. K. Bandyopadhyay, L. Goirand, J. Jacob, D. Jalas, B. Ogier, A. Triantafyllou
    ESRF, Grenoble
  • N. Guillotin
    SOLEIL, Gif-sur-Yvette
 
  At the ESRF, longitudinal coupled bunch instabilities driven by cavity HOM are currently avoided up to the nominal current of 200 mA by precisely controlling the temperatures of the six five-cell cavities installed on the storage ring. A longitudinal bunch by bunch feedback has recently allowed to overcome the remaining HOM and thereby increase the current in the storage ring to 300 mA. In parallel, HOM damped room-temperature cavities are being developed for highly reliable passive operation at 300 mA. They are designed for a possible later upgrade to higher currents.  
MOPP109 Status of the 100 MeV Preinjector for the ALBA Synchrotron 811
 
  • A. Falone, D. Einfeld, M. Pont
    ALBA, Bellaterra
  • D. Jousse, J.-L. Pastre, F. Rodriguez, A. S. Setty
    THALES, Colombes
  • A. Sacharidis
    EuroMev, Buc
 
  A turn key 100 MeV linac has been constructed by THALES in order to inject electrons into the booster synchrotron of ALBA*. The linac will be commissioned in May 2008. This paper will remind the main features of the linac** and will give results obtained during the commissioning tests. The energy and emittance measurements will be done on the transfer line conceived and realized by CELLS.

* D. Einfeld "Status of ALBA", PAC07, Albuquerque, USA, June 2007.
** A. Setty "Beam dynamics of the 100 MeV preinjector for the spanish synchrotron ALBA", PAC07, Albuquerque, USA, June 2007.

 
MOPP110 The SNS Resonance Control Cooling System Control Valve Upgrade Performance 814
 
  • D. C. Williams, J. P. Schubert, J. Y. Tang
    ORNL, Oak Ridge, Tennessee
 
  The normal-conducting linac of the Spallation Neutron Source (SNS) uses 10 separate Resonance Control Cooling System (RCCS) water skids to control the resonance of 6 Drift Tube Linac (DTL) and 4 Coupled Cavity Linac (CCL) accelerating structures. The RCCS water skids use 2 control valves; one to regulate the chilled water flow and the other is used to bypass water to a heat exchanger. These valves have hydraulic actuators that provide position and feedback to the control system. Frequency oscillations occur using these hydraulic actuators due to their coarse movement and control of the valves. New air actuator control positioners have been installed on the DTL3 RCCS water skid to give finer control and regulation of DTL3 cavity temperature. This paper shows a comparison of resonance control performance for two valve configurations.  
MOPP111 Beam Tests with the MAFF IH-RFQ at the IAP-Frankfurt 817
 
  • H. Z. Zimmermann, D. Habs
    LMU, Garching
  • A. Bechtold, P. Kolb, A. Schempp
    IAP, Frankfurt am Main
 
  The IH-type RFQ for the MAFF project at the LMU Munich is integrated into a test bench at the IAP in Frankfurt. The existing IH-RFQ set-up is the second after the HIS at GSI and the first one that can be directly compared to a very similar 4-rod type machine, the REX-ISOLDE RFQ at CERN. The test bench consists of an ionsource, an electrostatic quadrupole lens system with implemented steerers, and several beam diagnostic like a two dimensional emittance scanner, bending magnet and a fast faraday cup. Experimental results will be presented. These tests accompanied with theoretical investigations will be done with special respect to the applicability of such normal conducting RFQ accelerators to the EURISOL post accelerator.  
MOPP112 Status of the PEFP Superconducting RF Project 820
 
  • S. An, Y.-S. Cho, B. H. Choi, C. Gao, Y. M. Li, Y. Z. Tang, L. Zhang
    KAERI, Daejon
 
  Superconducting RF project of the Proton Engineering Frontier Project (PEFP) aims to develop a superconducting RF linac to accelerate a proton beam above 80 MeV at 700 MHz. The preliminary design of a low-beta cryomodule has been completed. A low-beta (β=0.42) cavity, a higher-mode coupler and a fundamental power coupler (FPC) for the PEFP cavities have also been designed. A FPC baking system and high power RF conditioning system are under construction. A helium vesel made of stainless steel has been designed. A new tuner has also been designed. Two prototype copper cavities have been produced and tested. The HOM coupler has been measured on the copper cavities. A cryostat for a SRF cavity vertical testing has been designed.  
MOPP113 PEFP Dumbbell Frequency and Length Tuning of a Low-beta SRF Cavity 823
 
  • S. An, Y.-S. Cho, C. Gao, Y. M. Li, Y. Z. Tang
    KAERI, Daejon
  • L. Zhang
    Department of Mechanics, Chang’an University, Daejon
 
  Based on present technology, a dumbbell fabrication is a necessary mid-process for a cavity manufacting process. A dumbbell with a right length and frequency is necessary to build up a desired cavity. In order to obtain the exact frequencies of each individual half cell of a PEFP dumbbell, a new and confirmed measurement method has been established. In this paper, the dumbbell frequency measurement method and the frequency and length tuning practices for a PEFP low-beta cavity have been described.  
MOPP114 Design of the Prototypical Cryomodule for the EUROTRANS Superconducting Linac for Nuclear Waste Transmutation 826
 
  • S. Barbanotti, N. Panzeri, P. Pierini
    INFN/LASA, Segrate (MI)
  • J.-L. Biarrotte, P. Blache, C. Commeaux, P. Duthil, E. Rampnoux
    IPN, Orsay
  • M. Souli
    GANIL, Caen
 
  One task of the accelerator workpackage of the EUROTRANS program for the design of a nuclear waste transmutation system is dedicated to the engineering and realization of a prototype cryomodule of the high energy section of the linac, equipped with elliptical superconducting niobium cavities. We review here the present status of the design and the planned program that foresees the experimental characterization of the fully equipped cavity and RF system under its nominal operating conditions.  
MOPP115 Production and Qualification of Low Thermal Conduction Suspension Supports for the Cold Mass of Long Superconducting Acceleration Modules 829
 
  • S. Barbanotti, M. Bonezzi, M. Todero
    INFN/LASA, Segrate (MI)
  • C. Engling, K. Jensch, R. Mattusch
    DESY, Hamburg
 
  A post is an assembly of a low thermal conduction composite material pipe (fiberglass pipe) and some shrink-fit aluminum and steel discs and rings, designed to provide a mechanical support and a thermal insulation to the cold mass of the long cryomodules of the TTF, which are foreseen also for the XFEL and ILC. We review here the production, testing and qualification for the production of post supports, which have been successfully provided for the cryomodules of the TTF in DESY, the STF in KEK and ILCTA in FNAL.  
MOPP116 Commissioning of the Cornell ERL Injector RF Systems 832
 
  • S. A. Belomestnykh, J. Dobbins, R. P.K. Kaplan, M. Liepe, P. Quigley, J. J. Reilly, C. R. Strohman, V. Veshcherevich
    CLASSE, Ithaca
 
  Two high power 1300 MHz RF systems have been developed for the Cornell University ERL Injector. The first system, based on a 16 kWCW IOT transmitter, is to provide RF power to a buncher cavity. The second system employs five 120 kWCW klystrons to feed 2-cell superconducting cavities of the injector cryomodule. The sixth, spare klystron is used to power a deflecting cavity in a pulsed mode for beam diagnostics. A digital LLRF control stem was designed and implemented for precise regulation of the cavities’ field amplitudes and phases. All components of these systems have been recently installed and commissioned. The results from the first turn-on of the systems are presented.  
MOPP117 First Test of the Cornell Single-cavity Horizontal Cryomodule 835
 
  • S. A. Belomestnykh, E. P. Chojnacki, R. Ehrlich, R. P.K. Kaplan, M. Liepe, V. Medjidzade, D. Meidlinger, H. Padamsee, P. Quigley, J. J. Reilly, D. M. Sabol, J. Sears, V. D. Shemelin, E. N. Smith, V. Veshcherevich, D. Widger
    CLASSE, Ithaca
 
  A single-cavity horizontal test cryomodule (HTC) has been designed and fabricated recently at Cornell University for ERL project. This cryomodule is a shortened version of the full injector cryomodule, which will house five superconducting cavities. It serves as a test bench for new design features and for testing fully dressed two-cell ERL injector cavities. The cryostat design has been optimized for precise cavity alignment, good magnetic shielding, and high cryogenic loads from the RF cavities, input couplers, and HOM loads. The HTC was made long enough so in the future it can accommodate longer, multicell cavities of the ERL main linac. In this paper we report on results from the first full test of the HTC, including RF system and superconducting cavity performance, cryomodule studies and operation of a new 1.8 K cryogenic system.  
MOPP120 Full Characterization of the Piezo Blade Tuner for Superconducting RF Cavities 838
 
  • A. Bosotti, C. Pagani, N. Panzeri, R. Paparella
    INFN/LASA, Segrate (MI)
  • C. Albrecht, K. Jensch, R. Lange, L. Lilje
    DESY, Hamburg
  • J. Knobloch, O. Kugeler, A. Neumann
    BESSY GmbH, Berlin
 
  Cavity tuners are mechanical devices designed to precisely match the resonant frequency of the superconducting (SC) cavity to the RF frequency synchronous with the beam. The blade tuner is mounted coaxially to the cavity and changes the resonator frequency by varying its length. A high tuning range is desired together with small mechanical hysteresis, to allow easy and reproducible resonator setup operations. High stiffness is also demanded to the tuner system both to ensure mechanical stability and to mitigate the frequency instabilities induced by perturbations. In high gradient SC resonators, the main sources of resonant frequency instability are the Lorentz Force Detuning (LFD) under pulsed mode operation, and the microphonic noise, in continuous wave (CW) with high loaded quality factors. Piezoceramic elements add dynamic tuning capabilities to the system, allowing fast compensation of these instabilities with the help of feed-forward and feedback loops. The piezo blade tuner has been extensively tested both at room temperature and at cold once assembled on a TESLA type cavity in its final configuration. This paper presents the summary of the complete characterization tests.  
MOPP121 Full Real-time Temperature Mapping System for 9-cell ILC-type Cavities 841
 
  • A. Canabal, F. L. Krawczyk, R. J. Roybal, J. D. Sedillo, T. Tajima
    LANL, Los Alamos, New Mexico
  • S. Cohen
    Bira, Albuquerque, New Mexico
  • W. Haynes
    Fermilab, Batavia, Illinois
 
  The mapping of outer-wall temperatures during the vertical test of a superconducting radio-frequency (SRF) cavity has been one of the most successful tools in detecting the cavities’ critical hot spots. However, due to the excessive number of sensors needed, no fixed-type temperature mapping (T-mapping) system that covers all cells has been built for 9-cell cavities. With the consensus that T-mapping analysis is needed in order to improve the yield of high-gradient cavities, a system with a reduced data acquisition time and increased temperature sensitivity, compared to rotating-arm systems, has been developed at Los Alamos National Laboratory. The system consists of ~5,000 100 Ω 1/8W Allen-Bradley resistors placed azimuthally every 10 degrees, a similar number of other resistors and diodes that implement the switching scheme, and data acquisition codes written in Labview. The details of the system and first results are presented and discussed.  
MOPP123 Design and Fabrication of the Cornell ERL Injector Cryomodule 844
 
  • E. P. Chojnacki, S. A. Belomestnykh, Z. A. Conway, J. J. Kaufman, M. Liepe, V. Medjidzade, D. Meidlinger, H. Padamsee, P. Quigley, J. Sears, V. D. Shemelin, V. Veshcherevich
    CLASSE, Ithaca
 
  The Energy Recovery Linac (ERL) development effort at Cornell will first produce an ERL beam source. The source will consist of a DC photo-gun, a buncher cavity, beam optics, and then an SRF Injector cryomodule to accelerate the 33-100 mA cw beam from 0.3-0.5 MeV to 5-15 MeV. The Injector cryomodule is based on TTF III technology with modifications to allow cw operation and the flexibility to accommodate the wide range of beam currents, bunch lengths, and beam energy. To deliver the 0.5 MWCW average power to the beam, the Injector cryomodule will contain five SRF 2-cell cavities, each cavity having two 50 kWCW coax couplers to deliver power from 100 kWCW klystrons, of which there are five for the Injector. Both the couplers and klystrons have been tested with 30% overhead in performance. Cold beamline HOM loads are placed between each cavity and outboard of the first and last cavities. Details of the Injector cryomodule design will be presented along with insight gained from the fabrication process, which will benefit the future ERL Linac cryomodule design and proto-typing.  
MOPP124 Commissioning of the 400 MHz LHC RF System 847
 
  • E. Ciapala, L. Arnaudon, P. Baudrenghien, O. Brunner, A. Butterworth, T. P.R. Linnecar, P. Maesen, J. C. Molendijk, E. Montesinos, D. Valuch, F. Weierud
    CERN, Geneva
 
  The installation of the 400 MHz superconducting RF system in LHC is finished and commissioning is under way. The final RF system comprises four cryomodules each with four cavities in the LHC tunnel. Also underground in an adjacent cavern shielded from the main tunnel are the sixteen 300 kW klystron RF power sources with their high voltage bunkers, two Faraday cages containing RF feedback and beam control electronics, and racks containing all the slow controls. The system and the experience gained during commissioning will be described. In particular, results from conditioning the cavities and their movable main power couplers and the setting up of the low level RF feedbacks will be presented.  
MOPP125 A Superconducting RF Vertical Test Facility at Daresbury Laboratory 850
 
  • P. A. Corlett, R. Bate, C. D. Beard, B. D. Fell, P. Goudket, S. M. Pattalwar
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • P. K. Ambattu, G. Burt, A. C. Dexter, M. I. Tahir
    Cockcroft Institute, Lancaster University, Lancaster
 
  A superconducting RF vertical test facility (VTF) has been constructed at Daresbury Laboratory for the testing of superconducting RF cavities at 2K. When fully operational, the facility will be capable of testing a 9-cell 1.3 GHz Tesla type cavity. The facility is initially to be configured to perform phase synchronisation experiments between a pair of single cell 3.9GHz ILC crab cavities. These experiments require the cavities to operate at the same frequency; therefore a tuning mechanism has been integrated into the system. The system is described, and data from the initial operation of the facility is presented.  
MOPP126 Experimental Characterization of a 700 MHz β=0.47 5 Cell Superconducting Cavity Prototype for Pulsed Proton Linac 853
 
  • G. Devanz, J.-P. Charrier, S. Chel, Y. Gasser, P. Hardy, J. Plouin, J. P. Poupeau, D. Roudier
    CEA, Gif-sur-Yvette
 
  A 700 MHz 5 cell elliptical cavity has been developed to accelerate a high intensity proton beam in the lower energy part of a superconducting linac, starting at 80 MeV. The cavity is stiffened in order to minimize the Lorentz detuning which limits high field pulsed operation of the flatter, low beta elliptical cavities. It is equipped with a stainless steel helium vessel. The RF tests of the cavity have been carried out at 1.8 K. Cavity performance is reported in this paper. Measurements of the RF response to mechanical excitations are also presented.  
MOPP127 Commissioning of Superconducting Linac at IUAC - Initial Challenges and Solutions 856
 
  • S. Ghosh, S. Babu, J. Chacko, A. Choudhury, G. K. Chowdhury, T. S. Datta, D. Kanjilal, S. Kar, M. Kumar, A. Mandal, D. S. Mathuria, R. S. Meena, R. Mehta, K. K. Mistri, A. Pandey, P. Patra, P. N. Prakash, A. Rai, A. Roy, B. K. Sahu, S. S. Sonti, J. Zacharias
    IUAC, New Delhi
 
  During initial acceleration of ion beam through the first module of linac having eight superconducting (SC) niobium quarter wave resonators (QWR), energy gains were found to be much lower. Major problem encountered was limitation of accelerating fields in the QWR achieved at much higher RF power (up to 300 W) leading to cable melting, metal coating on SC surface and increased cryogenic losses. Cold leaks in the niobium-stainless steel transition assemblies and niobium tuner bellows also posed a major challenge. A novel way of damping mechanical vibration was implemented to reduce RF power. Cooling was improved by installing a hemispherical structure on the resonator. The drive coupler was redesigned to eliminate metal coating. Design of the tuner/transition flange assemblies was modified to avoid cold leak. After incorporation of these modifications, on-line beam acceleration through Linac was accomplished. Pulsed (1.3 ns) Silicon beam of 130 MeV from Pelletron accelerator was further bunched to 250 ps by SC Superbuncher. After acceleration through the linac module and subsequent re-bunching using SC Rebuncher, 158 MeV Silicon beam having pulse width of 400 ps was delivered.  
MOPP128 Comparison of Stretched-wire, Bead-pull and Numerical Impedance Calculations on 3.9 GHz Dipole Cavities 859
 
  • P. Goudket, C. D. Beard, P. A. McIntosh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • G. Burt, A. C. Dexter
    Cockcroft Institute, Lancaster University, Lancaster
  • R. M. Jones
    Cockcroft Institute, Warrington, Cheshire
 
  In order to verify detailed impedance and wakefield simulations, the resonant modes in an aluminium model of the 9-cell ILC crab cavity were investigated using a stretched-wire frequency domain measurement, as well as frequency-domain bead-pull measurements. These measurements were compared to numerical simulations in order to verify that the complete cavity mode spectrum could be experimentally characterised for this high frequency structure. The analysis of the results and the accuracy and/or limitations of each method is presented.  
MOPP129 Compensation of Lorentz Force Detuning for SC Linacs (with Piezo Tuners) 862
 
  • M. K. Grecki, J. Andryszczak, T. Pozniak, K. P. Przygoda, P. M.S. Sekalski
    TUL-DMCS, Łódź
 
  The superconducting linacs use niobium cavities working with extremely high quality factor. Therefore the bandwidth of the cavity is very narrow and even subtle deformation caused by Lorentz force detunes the cavity a lot. For high gradient operation (over 15MV/m) the mechanical deformation of the cavity should be compensated by piezo tuner*. The paper presents design of a piezo control system and the results of measurements of its efficiency. It was demonstrated in FLASH accelerator that an initial detuning of 300Hz can be compensated by single pulse excitation of the piezo. The described system consist of multichannel programmable pulse generator driving a 8 channel piezo amplifiers capable to supply piezos with pulses up to 1A and up to 80V. It can compensate for Lorentz force detuning in all three FLASH cryhomodules equipped with piezos (ACC3,5,6).

*Liepe et al. "Dynamic Lorentz Force Compensation with a Fast Piezoelectric Tuner," PAC2001, pp. 1074-1076.

 
MOPP130 SRF Technology-Past, Present and Future Options 865
 
  • G. Myneni, M. Hutton
    Jefferson Lab, Newport News, Virginia
 
  Superconducting radiofrequency cavities for all recent projects (CEBAF, SNS, KEKB, and TTF) have been built from high purity polycrystalline niobium with a residual resistance ratio (RRR) greater than 250. The procedures and processes used from the initial production of the high RRR polycrystalline niobium sheets to the finished cavities are complex, numerous and very expensive, and the yield of SRF cavities meeting the performance specifications is very low. CBMM – Jefferson Lab invented the large grain and single crystal niobium technologies, and the use of niobium sliced directly from the ingots is expected to change the SRF technology outlook with fewer, and more streamlined, production processes that will not only be cost effective but also generate high yield. In this paper we will show that less stringent commercial niobium specifications are required, and explore the processes and procedures that will lay the foundation for producing SRF cavities with good quality factors at high peak magnetic fields in order to make this technology friendlier for future scientific and technological applications.  
MOPP131 Cryomodule Tests of the STF Baseline 9-cell Cavities at KEK 868
 
  • E. Kako, H. Hayano, S. Noguchi, N. Ohuchi, M. Sato, T. Shishido, K. Watanabe, Y. Yamamoto
    KEK, Ibaraki
 
  The STF-Baseline superconducting cavity system, which includes four TESLA-type 9-cell cavities, input couplers and frequency tuners, has been developed for the future ILC project. A 6m-cryomodule including one of four STF-Baseline cavities was assembled for the initial test called the STF Phase -0.5. The first cool-down of the cryomodule and high power tests of the STF-Baseline cavity had been successfully carried at 2 K. The maximum accelerating gradient (Eacc,max) of 19.3 MV/m was achieved in a specific pulse width of 1.5 msec and a repetition of 5 Hz, (23.4 MV/m in a shorter pulse of 0.6 msec). The onset of x-rays radiation was observed at higher field than 15 MV/m, and the measured Qo value was about 5 x 109 at 18 MV/m in accompanied with field emission. The detuning angle of about -13 degrees at 18 MV/m was successfully compensated to nearly zero by a combined operation with both an offset detuning and an optimised applied voltage in the piezo element. String assembly of four STF-Baseline cavities has been stated in Jan. 2008. The second cryomodule test for 4 cavities, called the STF Phase -1.0, is scheduled in this early summer.  
MOPP132 Progress Towards Development of an L-Band SC Traveling Wave Accelerating Structure with Feedback 871
 
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • P. V. Avrakhov
    LPI, Moscow
  • S. Kazakov
    KEK, Ibaraki
  • N. Solyak, V. P. Yakovlev
    Fermilab, Batavia, Illinois
 
  We describe an ongoing experimental program and progress towards development of a conceptual design for a superconducting traveling wave accelerating structure for the ILC. The accelerating gradient can be significantly improved by the use of an RF feedback system redirecting the accelerating wave that passed through the superconducting traveling wave accelerator (STWA) section back to the input of the accelerating structure. The conceptual design of the SC traveling wave accelerator has been considered by P. Avrakhov et al. [PAC07, pp.2538], where shape optimization, coupler cell design and tuning issues in the feedback loop were presented. The proposed TW structure design gives an overall 24% increase in gradient over the 1 m long standing wave structure and potentially can reach 46% if a longer structure is employed. Experimental investigation of the TW SC structure considers tests of a single cavity having the same shape as the regular cell of the full-sized STWA structure, and the same ratio of the RF fields. The details of the individual parts, joint configurations along with some developments on forming and welding of the proposed cavity shapes are discussed.  
MOPP135 Vertical and Horizontal Test Results of 3.9 GHz Accelerating Cavities at FNAL 874
 
  • T. N. Khabiboulline, H. T. Edwards, M. H. Foley, E. R. Harms, A. Hocker, D. V. Mitchell, A. M. Rowe, N. Solyak
    Fermilab, Batavia, Illinois
 
  The 3rd harmonic 3.9GHz accelerating cavity was proposed to improve the beam performance of the electron/positron linear accelerators. In the frame of a collaborative agreement, Fermilab will provide DESY with a cryomodule containing a string of four cavities. Several 9-cell Nb cavities were tested and they did reach accelerating gradient up to 24 MV/m almost twice more than design value of 14 MV/m. Two of these cavities are with new HOM couplers with improved design. In this paper we present all results of the vertical and horizontal tests.  
MOPP136 Performance of Single Crystal Niobium Cavities 877
 
  • P. Kneisel, G. Ciovati
    Jefferson Lab, Newport News, Virginia
  • A. Brinkmann, D. Reschke, W. Singer, X. Singer
    DESY, Hamburg
 
  We have fabricated and tested a total of six single cell niobium cavities, made from single crystal, high purity niobium. Two of the three cavities of the TESLA shape (1300 MHz) were made from Heraeus niobium by extending a smaller single crystals by rolling and annealing steps; the third cavity was made by spinning. The three other cavities of the scaled LL shape (2) and TESLA shape (1) resonated at 2.3 GHz and were fabricated from “as received” single crystals, both from Heraeus and CBMM niobium. After appropriate surface treatments by buffered chemical polishing and electropolishing all cavities performed quite nicely and peak surface magnetic fields of ~ 160 mT or above corresponding to accelerating gradients between 38 MV/m and 45 MV/m were reached. This paper reports about the performance of these cavities.  
MOPP137 MultiPac 2.1 - Multipacting Simulation Package with a 2D FEM Field Solver for a Microsoft Windows System 880
 
  • Y. M. Li, S. An, Y.-S. Cho, L. Zhang
    KAERI, Daejon
  • P. Ylä-Oijala
    Helsinki University of Technology, Helsinki
 
  MultiPac 2.1 is a multipacting simulation package for analyzing electron multipacting in axisymmetric RF structures with TM0nl mode, such as RF cavities, coaxial input couplers and ceramic windows. The original package was written by P. Ylä-Oijala*, and works with MATLAB 5.0 or 6.0 on Linux operating system. In order to use this code easily for Microsoft Windows customers, we have transferred the MultiPac 2.1 from the Linux system to the Microsoft Windows system. The revised MultiPac can work with Microsoft Windows MatLab 6.0 or later editions smoothly. In this paper, the installation and operation of the Windows MutiPac 2.1 have been introduced.

*This work was supported by the 21C Frontier R&D program in Ministry of Science and Technology of the Korean Government.

 
MOPP138 First Test Results from the Cornell ERL Injector Cryomodule 883
 
  • M. Liepe, S. A. Belomestnykh, E. P. Chojnacki, Z. A. Conway, R. Ehrlich, R. P.K. Kaplan, V. Medjidzade, H. Padamsee, P. Quigley, J. J. Reilly, D. M. Sabol, J. Sears, V. D. Shemelin, E. N. Smith, V. Veshcherevich, D. Widger
    CLASSE, Ithaca
 
  Cornell University has developed and fabricated a 5 cavity SRF injector cryomodule for the acceleration of a high current (100 mA), ultra low emittance beam. This cryomodule has been installed in the Cornell ERL prototype, and is presently under extensive test. The combination of a high beam current with emittance preservation of an ultra low emittance beam results in a multitude of challenges for the SRF system, pushing parameters well beyond present state of the art. Strong HOM damping and effective HOM power extraction is required to support the 100 mA beam current. This is achieved by placing HOM beam line absorbers between all cavities. Emittance preservation is addressed by a symmetric beam line with twin input couplers, tight cavity alignment and the option of fine alignment of cold cavities. In this paper we report on first results from the injector module test, including cavity performance tests, static heat load measurements and microphonic studies.  
MOPP140 Status and Test Results of High Current 5-cell SRF Cavities Developed at JLAB 886
 
  • F. Marhauser, G. Cheng, G. Ciovati, W. A. Clemens, E. Daly, D. Forehand, J. Henry, P. Kneisel, S. Manning, R. Manus, R. A. Rimmer, C. Tennant, H. Wang
    Jefferson Lab, Newport News, Virginia
 
  A new compact CW cryomodule development for use in future ERLs and FELs is underway at JLAB. Five-cell SRF cavities have been built at 1497 MHz for moderate RF input power scenarios with waveguide endgroups to efficiently transfer the beam induced HOM energy to room temperature loads. Effort has been made as well to provide a good real-estate gradient, cryogenic efficiency and HOMs tuned to safe frequencies to minimize HOM power extracted from the beam. Preliminary tests carried out earlier for two single-cell cavities at 1497 MHz cavity -one with a waveguide endgroup- and a bare 1497 MHz five-cell cavity have exceeded gradient and Qo specifications with no signs of multipacting and encouraged us to built two fully equipped 1497 MHz five-cell cavities. We report on the latest test results and the HOM impedance budget of the cavity used to evaluate BBU limits based on special machine optics.  
MOPP141 Commissioning of the ERLP SRF Systems at Daresbury Laboratory 889
 
  • P. A. McIntosh, R. Bate, R. K. Buckley, S. R. Buckley, P. A. Corlett, A. J. Moss, J. F. Orrett, S. M. Pattalwar, A. E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • F. G. Gabriel
    FZD, Dresden
  • A. R. Goulden
    STFC/DL/SRD, Daresbury, Warrington, Cheshire
  • P. vom Stein
    ACCEL, Bergisch Gladbach
 
  The Energy Recovery Linac Prototype (ERLP) has been installed at Daresbury Laboratory and its baseline commissioning completed. The SRF systems for ERLP comprise two 9-cell, 1.3 GHz accelerating cavities in the injector (or Booster) cryomodule, which provide a nominal energy gain of 8 MeV for the injected 350 keV beam from the photo-injector. The beam is then accelerated in an identical two cavity cryomodule in the energy recovery main Linac, giving a final ERLP energy of 35 MeV. Each SRF accelerating cavity is powered by commercially available Inductive Output Tubes (IOTs) and the analog LLRF control system is identical to that employed on the ELBE facility at FZD Rossendorf. This paper details the commissioning experience gained for these systems and highlights the ultimate performance achieved.  
MOPP144 The First Cool-down Tests of the 6 Meter-Long-Cryomodules for Superconducting RF Test Facility (STF) at KEK 892
 
  • N. Ohuchi, F. Furuta, K. Hara, H. Hayano, N. Higashi, Y. Higashi, H. Hisamatsu, K. Hosoyama, E. Kako, Y. Kojima, M. Masuzawa, H. Matsumoto, H. Nakai, S. Noguchi, T. Saeki, K. Saito, T. Shishido, A. Terashima, N. Toge, K. Tsuchiya, K. Yokoya
    KEK, Ibaraki
  • M. H. Tsai
    NSRRC, Hsinchu
  • Q. J. Xu
    IHEP Beijing, Beijing
 
  KEK is presently constructing the Superconducting RF Test Facility (STF) as the center of the ILC-R&D in Asia from 2005. In this project, KEK aims to get the manufacturing and operational experiences of the RF cavity and cryomodule toward the ILC, and two cryomodules have been developed. These cryomodules are 6 meter long and have 4 nine-cell cavities in each cryostat. The basic cross section designs of the cryomodules are almost same as the design of TESLA type-III, however, each cryostat has the different type of cavities, TESLA type and Low-Loss type. The tests for the cryomodules are planed to be performed at three steps. In the first test, measurements of the cryogenic performances of these cryomodules are the main objective. One nine-cell cavity was assembled in each cryostat and the cool-down of the two cryomodules was performed. In the following tests, the four nine-cell cavities will be assembled in each cryostat as the complete integration and the beam test will be performed. In this paper, we will report the design of the cryomodules and the cryogenic performances at the first cold test.  
MOPP146 The Coaxial Tuner for ILCTA_NML at Fermilab 895
 
  • A. Bosotti, C. Pagani, N. Panzeri, R. Paparella
    INFN/LASA, Segrate (MI)
 
  The piezo Blade Tuner prototype has been successfully tested inside the horizontal cryostat, CHECHIA, at DESY and extensive tests at BESSY are planned. As suggested by the cold test results, a few minor modifications have been implemented and a set of 8 improved devices is under construction for the installation in the second module of ILCTA at Fermilab. This reviewed design, together with a simplified helium tank in prototyping, should hopefully fulfill also the XFEL requests in term of performances and cost. In particular the use of thicker blades and their slightly different distribution along the circumference produces the increase of the tuner strength and stiffness that is needed in order to fulfill the pressure vessel regulations for qualification. As in the past, two equivalent devices, respectively in titanium and stainless steel, have been designed to maintain open the possibility of the use of a SS helium vessel once the required technology were developed. The results of the extensive mechanical tests performed to validate the estimated performances and life time are also presented.  
MOPP148 Design of a Magnetic Shield Internal to the Helium Vessel of SRF Cavities 898
 
  • P. Pierini, S. Barbanotti, L. Monaco, N. Panzeri
    INFN/LASA, Segrate (MI)
 
  The TRASCO elliptical cavities for intermediate velocity protons (β=0.47) employ a coaxial cold tuner of the blade type. To meet the perfomance goals of the 700 MHz cavities in the foreseen horizontal cryostat tests, the cavities are being equipped with a magnetic shield which lies internally to the cavity helium vessel and has a simple mechanical design and assembly procedure.  
MOPP149 Recent Developments of the Superconducting CH-Cavities 901
 
  • H. Podlech, A. Bechtold, M. Busch, F. Dziuba, H. Liebermann, U. Ratzinger
    IAP, Frankfurt am Main
 
  The Crossbar-H-mode (CH)-structure which has been developed at the IAP in Frankfurt is a multi-cell drift tube structure for the efficient acceleration of low and medium energy protons and ions. The superconducting low energy CH-prototype cavity has reached gradients of up to 7 MV/m, corresponding to an effective voltage gain of 5.6 MV. This shows that high real estate gradients can be achieved in superconducting low energy multi-cell cavities. Additionally, microphonics and tuning measurements have been performed at room temperature and at 4K. Optimized cavity geometry for high power beam projects and plans for the construction of a new superconducting cavity will be presented.  
MOPP152 Bunch Lengthening Harmonic System for NSLS-II 904
 
  • J. Rose, N. A. Towne
    BNL, Upton, Long Island, New York
 
  NSLS-II is a new ultra-bright 3GeV 3rd generation synchrotron radiation light source. The performance goals require operation with a beam current of 500mA and a bunch current of at least 0.5mA. Ion clearing gaps are required to suppress ion effects on the beam. The natural bunch length of 3mm is planned to be lengthened by means of a third harmonic cavity in order to provide a margin for the Touschek limited lifetime and for instability threshold currents. The paper presents the analysis of the bunch lengthening in this dual RF system consisting of a 500MHz fundamental and 1500 MHz harmonic system in presence of strong transient beam loading. A conceptual design of a 1500MHz SCRF cavity is developed and design performance is discussed.  
MOPP153 Cavity Diagnostics Using Rotating Mapping System for L-band ERL Superconducting Cavity 907
 
  • H. Sakai, K. Shinoe
    ISSP/SRL, Chiba
  • T. Furuya, T. Takahashi, K. Umemori
    KEK, Ibaraki
  • M. Sawamura
    JAEA/ERL, Ibaraki
 
  We are developing the L-band superconducting cavity for Energy Recovery Linac in Japan. In order to survey the electron emission and the heating spot of the cavity inner surface in detail, cavity diagnostics with the rotating mapping system was applied for the vertical tests of our cavities. Two types of sensor, one of which is the carbon resistor and the other is the Si PIN photo diode, was equipped to detect the temperature rise and electron emission. These two sensor arrays were arranged along the cavity axis and set on the rotating mechanics with servo motor. By rotating the sensor arrays around the cavity axis, a lot of information is obtained all over the cavity surface in detail. It is preferable that the number of sensors will be reduced compared with the usual cavity mapping system by using this rotating mapping system. We have already fabricated the Nb single cell cavities which is optimised for ERL operation and then performed the vertical test of Nb ERL single cell cavities. This paper reports the results of the mapping system with Nb single cell ERL-shape cavities.  
MOPP154 Study of the High Pressure Rinsing Water Jet Interactions 910
 
  • D. Sertore, M. Fusetti, P. M. Michelato, C. Pagani
    INFN/LASA, Segrate (MI)
 
  High Pressure Rinsing (HPR) is an important step in the cleaning of Superconducting Cavities (SC). The understanding of the interaction of the high pressure water jet on the cavity wall is of primary importance for the optimization of this process for upcoming SC based projects like XFEL and ILC. In this paper, we extend our results obtained so far in different labs and present our studies on water jet interaction on oblique surfaces and the possible induced damages.  
MOPP155 Superconducting RF Deflecting Cavity Design and Prototype for Short X-ray Pulse Generation 913
 
  • J. Shi, H. Chen, C.-X. Tang
    TUB, Beijing
  • G. Cheng, G. Ciovati, P. Kneisel, R. A. Rimmer, G. Slack, L. Turlington, H. Wang
    Jefferson Lab, Newport News, Virginia
  • D. Li
    LBNL, Berkeley, California
  • A. Nassiri, G. J. Waldschmidt
    ANL, Argonne, Illinois
 
  Deflecting RF cavities are proposed to be used in generating short x-ray pulses (on ~1-picosecond order) at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL)* using a novel scheme by Zholents**. To meet the required deflecting voltage, impedance budget from higher order, lower order and the same order modes (HOM, LOM and SOM) of the APS storage ring, extensive deflecting cavity design studies have been conducted with numerical simulations and cavity prototypes. In this paper, we report recent progress on a single cell S-band (2.8-GHz) superconducting deflecting cavity design with waveguide damping. A copper and a niobium prototype cavity were fabricated and tested, respectively to benchmark the cavity and damping designs. A new damping scheme has been proposed which provides stronger damping to both HOM and LOM by directly coupling to a damping waveguide on the cavity equator.

* A. Nassiri, private communication, 2007
** A. Zholents et al. NIM, 1999, A425:385-389.

 
MOPP156 Fabrication and Low Power Testing of an L-band Deflecting Cavity for Emittance-exchange at ANL 916
 
  • J. Shi, H. Chen, W.-H. Huang, C.-X. Tang, D. Tong
    TUB, Beijing
  • W. Gai, C.-J. Jing, K.-J. Kim, J. G. Power
    ANL, Argonne, Illinois
  • D. Li
    LBNL, Berkeley, California
 
  An L-Band RF deflecting cavity has been built at Tsinghua University for a planned transverse-to-longitudinal emittance exchange experiment at Argonne National Laboratory (ANL). The deflector is a 1.3-GHz, 3-cell cavity operated in a TM110-like mode that delivers a deflecting voltage of 3.4 MV. In this paper, we review the cavity design and present detail of the fabrication, cold testing and tuning progress. Cell radii were left undercut to account for simulation errors, which yielded a higher frequency in the first bench measurement but removed by the final tuning on the lathe. Field distribution on axis was measured using the ‘‘bead-pull'' method and tuned to balance in the 3 cells.  
MOPP157 Critical Magnetic Field Determination of Superconducting Materials 919
 
  • A. Canabal, T. Tajima
    LANL, Los Alamos, New Mexico
  • V. A. Dolgashev, S. G. Tantawi
    SLAC, Menlo Park, California
  • T. Yamamoto
    UTNL, Ibaraki
 
  Using a 11.4 GHz, 50-MW, <1 μs, pulsed power source and a TE013-like mode copper cavity, we have been measuring critical magnetic fields of superconductors for accelerator cavity applications. This device can eliminate both thermal and field emission effects due to a short pulse and no electric field at the sample surface. A model of the system is presented in this paper along with a discussion of preliminary experimental data.  
MOPP158 Conceptual Design of Automated Systems for SRF Cavity Optical Inspection and Assembly 922
 
  • T. Tajima, A. Canabal, T. A. Harden, R. J. Roybal
    LANL, Los Alamos, New Mexico
 
  The International Linear Collider (ILC) will require ~16,000 Superconducting Radio-Frequency (SRF) cavities at an accelerating gradient of 31.5 MV/m. One of the critical issues that needs to be addressed is the insufficient yield of high-gradient cavities that meet the requirement. This paper describes the design and initial tests of a cavity inner surface optical inspection system. Combined with a full-featured 9-cell cavity temperature mapping system being developed at LANL, we hope to be able to correlate the cavity heating and the surface condition causing it.  
MOPP159 Results of Vertical Tests for the KEK-ERL Single Cell Superconducting Cavities 925
 
  • K. Umemori, T. Furuya, T. Takahashi
    KEK, Ibaraki
  • H. Sakai, K. Shinoe
    ISSP/SRL, Chiba
  • M. Sawamura
    JAEA/ERL, Ibaraki
 
  The development of the superconducting cavities is indispensable for realizing the 5 GeV-class energy recovery linacs. The KEK-ERL cavity had been recently designed. Its features are the optimized cell shapes and adoption of the enlarged beampipes with eccentric-fluted structures. In order to confirm our cavity design, two types of single cell cavities had been fabricated. One is a center-cell type cavity, whose aim is a validation of the cell shape, and another is an end-cell type cavity, which has complex structure such as the eccentric-fluted beampipes. After applying a series of surface treatments, we had assembled the cavities and performed vertical tests at KEK D10 area. Promising results have been obtained. In this presentation, we will present the results of vertical tests for these cavities.  
MOPP161 Plasma Etching Rates and Surface Composition of Bulk Nb Treated in Ar/Cl2 Microwave Discharge 928
 
  • M. Raskovic, S. Popovic, J. Upadhyay, L. Vuskovic
    ODU, Norfolk, Virginia
  • H. L. Phillips, A-M. Valente-Feliciano
    Jefferson Lab, Newport News, Virginia
 
  To achieve theoretically predicted values of the accelerating fields in superconducting radiofrequency (SRF) cavities, their inside surface should be fairly smooth and free of impurities. Thus, surface preparation is the critical step in production of SRF cavities. Plasma etching process is a dry chemistry technique that can be used to achieve these requirements. It is based on interaction between reactive halogen species produced in the glow discharge and the surface. During this process, volatile Nb halides are evaporated from the surface of Nb, removing the mechanically damaged and contaminated layer. We present treatment of bulk Nb samples in the Ar/Cl2 microwave discharge. We achieved etching rates comparable to the rates obtained with the electropolishing method without introducing impurities in Nb. The rate dependence on various discharge parameters and reactive gas composition is presented. Surface composition and topology measurements were carried out before and after plasma treatment to determine level of impurities. Optimal experimental conditions determined on samples will applied be on single cell cavities, pursuing improvement of their RF performance.  
MOPP162 Titanium Nitride Coating of RF Ceramic Windows by Reactive DC Magnetron Sputtering 931
 
  • V. Variola, H. Jenhani, W. Kaabi, P. Lepercq
    LAL, Orsay
  • G. Keppel, V. Palmieri, F. Strada
    INFN/LNL, Legnaro, Padova
 
  Alumina is a common material for RF windows. Besides its high dielectric strength, it is stable under thermal treatment and has a low out-gassing rate. Nevertheless it has a high secondary electron emission (SEE) coefficient, which leads to multipactor limiting the achievable RF power. One way to suppress the multipactor on RF windows is to coat it with a low SEE-thin TiN film. In the frame of the LAL coupler program a sputtering bench has been developed. It is equipped with two magnetrons and titanium targets. A special rotating holder was designed to allow uniform deposition on cylindrical windows. RF etching of the substrate as a pre-treatment step is allowed, in order to remove particle contamination and to increase TiN adhesion. The TiN sputtering needs the optimisation of gas and electrical parameters. XRD analysis was performed to check the film composition and stoechiometry. The results show how to control the N2 vacancy acting on the gas flow. In addiction, the coating thickness must be optimized not to cause excessive ohmic heating, so multipactor thresholds measurements were done for different coating thickness. Thickness measurments showed a good uniformity.  
MOPP164 Improvements in Field Emission: A Statistical Model for Electropolished Baked Cavities 934
 
  • J. L. Wiener, H. Padamsee
    Cornell University, Ithaca, New York
 
  A statistical model for field emission developed in 1993 has been applied to characterize the improvement in field emitter properties and field emitter occurrence due to improvements in treatment methods for 9-cell TESLA-style cavities. The improved treatments are electropolishing, high pressure rinsing and baking (120C, 48 hours). We model the Q vs. Eacc data from 24 9-cell tests and 32 1-cell tests, all conducted at TTF by DESY. The statistical model is able to successfully simulate the observed yields by applying a factor of 3 decrease in emitter density over the emitter density prevailing for treatments in 1993, which did not include high pressure rinsing. Both simulation and data show that at Eacc = 70 MV/m the yield for field emission power less than 100 watts (Q > 8x109) is less than 20%. To raise this yield to 80% will require new treatments that will reduce the emitter density by another factor of 3 at least. Further comparisons of field emission behavior will be made with data for alcohol rinsed cavities.  
MOPP165 FZJ Smallest SC Triple-Spoke Cavity 937
 
  • E. Zaplatin, W. Braeutigam, M. Pap, M. Skrobucha
    FZJ, Jülich
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
 
  The paper describes the design, fabrication and test results of the smallest triple-spoke cavity (resonant frequency 760 MHz, β=0.2) developed at Forschungszentrum Juelich.  
MOPP166 Control System for a PEFP FPC Baking System 940
 
  • L. Zhang, S. An, Y.-S. Cho, Y. M. Li, Y. Z. Tang
    KAERI, Daejon
 
  In order to bake PEFP Fundamental Power Couplers (FPC) before their RF conditioning, a PEFP baking system has been designed. A control system for the baking system has been completed by using the Labview 8.2 and A-B SLC-500 PLC. In this paper, the server and client communication technology based on OLE for a Process Control (OPC) and a Labview 8.2 Datalogging and Supervisory Control (DSC) Module are described. The program for the SLC-500 PLC with four I/O modules has been written. The mechanical design and control process are described.  
MOPP168 Tests on the 1.3 GHz Low Loss Single-Cell RF Superconducting Large Grain Cavities of IHEP 943
 
  • Z. G. Zong, J. Gao, M. Q. Ge, J. Gu, H. Sun, D. Wang, Q. J. Xu, J. Y. Zhai, F. C. Zhao
    IHEP Beijing, Beijing
  • F. Furuta, T. Saeki, K. Saito
    KEK, Ibaraki
  • L. Q. Liu
    Technical Institute of Physics and Chemistry, Beijing
  • L.-Y. Xiong, L. Zhang, T. X. Zhao, Z. G. Zong
    TIPC, BeiJing
 
  To contribute to the International Linear Collider (ILC) R&D on the 1.3 GHz low loss cavities has been carried out at IHEP since 2005. Six cavities had been fabricated by the standard technology and treated by some procedures of surface treatments, such as centrifugal barrel polishing, barrel chemical polishing, annealing, high pressure rinsing and baking at in-house IHEP. Because of the shortage of liquid helium in Beijing two large grain cavities with a fine grain one were sent to KEK for vertical tests. The large grain cavities was tested and treated at KEk and finally both reached the accelerating gradients of more than 35 MV/m with the maximum of 40.27 MV/m. This paper presents the testing and results of the large grain cavities.