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dipole

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MOP007 Turn Around Loop and Chicane for Bunch Compression and Path Length Tuning in the CLIC Drive Beam emittance, electron, kicker, simulation 43
 
  • F. Stulle, A. Adelmann, M. Pedrozzi
    PSI, Villigen
  The phase feedback of the CLIC drive beam consists of phase and energy measurement stations in front of the turn around loops and chicanes for bunch compression and path length correction behind the loops. The chicanes are foreseen to compress the bunches from 4 mm to 0.4 mm and should allow a path length tuning of at least 0.1 mm. Suitable layouts for the turn around loops and the chicanes and results of beam dynamics simulations including incoherent and coherent synchrotron radiation are presented.  
 
MOP018 Upgrading the CEBAF Accelerator to 12 GeV: Project Status controls, linac, beam-transport, acceleration 70
 
  • L. Harwood
    Jefferson Lab, Newport News, Virginia
  Jefferson Lab is preparing to upgrade its 6 GeV Continuous Electron Beam Accelerator Facility (CEBAF) to 12 GeV as part of the 12 GeV Upgrade project. The doubled energy will significantly extend the scientific reach of the three existing Halls with upgraded experimental equipment, and will make possible a new research program in exotic mesons in a newly constructed fourth Hall. The acceleration of the present linacs will be roughly doubled through the addition of ten new cryomodules with performance ~5 times the original specification for CEBAF. The 2K helium plant will be roughly doubled; new rf systems, including digital controls, will be installed for the new cryomodules. The beam transport system’s capability will be doubled by strongly leveraging existing hardware (without incurring significant saturation) but must be enhanced with some replacement magnets, new power supplies, one new recirculation arc, and a beamline to the new Hall. Critical Decision 1 was approved by DOE for this project in February 2006. Technical status for the accelerator systems including R&D will be presented as well as the status of the 12 GeV Upgrade Project as a whole.  
 
MOP053 Construction of a High-Current RFQ for ADS Study rfq, vacuum, quadrupole, coupling 165
 
  • S. Fu, S. X. Fang, K. Y. Gong, J. Li, H. F. Ouyang, J. M. Qiao, T. G. Xu, W. W. Xu, X. A. Xu, Y. Yao, H. S. Zhang, Z. H. Zhang
    IHEP Beijing, Beijing
  • X. L. Guan
    CIAE, Beijing
  A high current RFQ accelerator has been constructed in China for the basic study of Accelerator Driven Subcritical System. The ADS project is supported by a national program and aimed at the development of clean nuclear energy to meet of the rapid growth of the nuclear power plants in China. The 3.5MeV RFQ accelerator has been fabricated and installed. Field tuning and high power conditioning indicate a good agreement with our design. The beam commissioning with an ECR ion source is under development. This paper will present the recent progress in the construction and commissioning of the RFQ accelerator.  
 
MOP055 Transport of LANSCE-Linac Beam to Proposed Materials Test Station target, quadrupole, diagnostics, emittance 171
 
  • B. Blind, K. F. Johnson, L. Rybarcyk
    LANL, Los Alamos, New Mexico
  Refurbishment of Experimental Area A and installation of a Materials Test Station is planned at the Los Alamos Neutron Science Center (LANSCE). This paper describes the beamline to transport 800-MeV protons from the accelerator to Area A. The beamline has the minimum number of quadrupoles necessary to achieve the desired instantaneous beam parameters at the target, the appropriate beam-centroid excursions at the split target for painting the two target halves, and a beam-centroid crossover upstream of the target to facilitate shielding of upstream components from backstreaming neutrons. Options in the composition of the raster-magnet section represent trade-offs between the number of magnets and the severity of the effects of magnet failures. Beam diagnostics are an integral part of the beamline design. Instantaneous and painted beam sizes at the target can be inferred by observing the beam at properly chosen upstream locations. A beamline spur to a tune-up beam dump is planned.  
 
MOP066 Wake Fields and Beam Dynamics Simulations for the 3.9-GHz Cavities of the ILC emittance, simulation, luminosity, damping 196
 
  • R. M. Jones
    UMAN, Manchester
  • L. Bellantoni
    Fermilab, Batavia, Illinois
  • G. Burt, A. C. Dexter
    Cockcroft Institute, Lancaster University, Lancaster
  • A. Latina, D. Schulte
    CERN, Geneva
  Crab cavities are used for the ILC in order to increase the luminosity of the colliding beams. These cavities operate at the 3rd harmonic of the accelerating frequency (1.3GHz). We study the LOM (Lower Order Modes) and HOM (Higher Order Modes) excited by the beam. The corresponding wake field is calculated and simulations are conducted on the beam dynamics of the interaction of the wake field with the multi-bunch beam train.  
 
TUP013 Using Higher Order Modes in Superconducting Accelerating Cavities for Beam Monitoring monitoring, controls, single-bunch, electron 271
 
  • N. Baboi, O. Hensler
    DESY, Hamburg
  • N. E. Eddy, S. Nagaitsev
    Fermilab, Batavia, Illinois
  • J. C. Frisch, S. Molloy, M. C. Ross
    SLAC, Menlo Park, California
  • O. Napoly, R. Paparella
    CEA, Gif-sur-Yvette
  Dipole modes have been shown to be successful diagnostics for the beam position in superconducting accelerating cavities at the VUV Free Electron Laser (FEL) facility at DESY. By help of downmixing electronics the signals from the two higher order mode couplers mounted on each cavity are monitored. Due to the non-symmetric placement of the couplers and the overlapping of the two polarizations of the modes, the calibration is somewhat more complicated than in standard position monitors. A method based on the model independent analysis has been developed. The calibration measurements made at the VUV FEL will be presented.  
 
TUP046 Experimental Studies of Electrostatic and Solenoidal Focusing of Low-Energy, Heavy-Ion ECRIS Beams at the NSCL/MSU emittance, focusing, ion, injection 352
 
  • J. W. Stetson, G. Machicoane, P. Miller, M. Steiner, P. A. Zavodszky
    NSCL, East Lansing, Michigan
  Replacement of the focusing solenoids between both ECR Ion Sources and the beam analysis dipoles with electrostatic triplets has resulted in a large increase in net accelerator output. 2D emittance scans explain some but not all of this increase. Further improvement is anticipated with a new optical device consisting of an electrostatic quadrupole doublet-octupole-doublet-magnetic sextupole arrangement, which has been built and is being tested in place of a triplet. Motivations and results of measurements and operating experience are discussed.  
 
THP008 Detailed Modeling of the SNS RFQ Structure with CST Microwave Studio rfq, simulation, SNS, quadrupole 580
 
  • D. Li, J. W. Staples, S. P. Virostek
    LBNL, Berkeley, California
  We report detailed RF modeling on the SNS RFQ structure using CST Microwave Studio code. Due to the complexity of the RFQ structure, a three-dimensional model with large mesh ratio is required to adequately model the necessary details of the structure. Old 3-D codes are not capable of giving accurate predictions of resonant frequency and fields, or for including mode stabilizers and terminations. A physical prototype is needed to verify resonant frequency and field profile, including mode stabilizers and end terminations, which is expensive and time consuming. Taking advantage of CST Microwave Studio’s new Perfect Boundary Approximation (PBA) technique, we constructed a 3-dimensional computational model based on the as-built SNS RFQ dimensions with pi-mode stabilizers, end cutbacks and tuners and simulated it in the frequency domain using the CST Eigenvalue Solver. Simulation results accurately predicted the resonant frequency and field distributions. We are applying the simulation technique to the design of another RFQ.  
 
THP046 Status of 3.9-GHz Deflecting-Mode (CRAB) Cavity R&D luminosity, simulation, beam-loading, positron 682
 
  • L. Bellantoni, H. Edwards, M. Foley, T. K. Khabiboulline, D. V. Mitchell, A. M. Rowe, N. Solyak
    Fermilab, Batavia, Illinois
  • C. Adolphsen
    SLAC, Menlo Park, California
  • G. Burt, A. C. Dexter
    Cockcroft Institute, Lancaster University, Lancaster
  • P. Goudket
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • T. W. Koeth
    Rutgers University, The State University of New Jersey, Piscataway, New Jersey
  The superconducting 3.9GHz deflecting mode cavity design which has been under development as a beam slice diagnostic is planned for use as the ILC crab cavity. We describe the applications and review the status of the R & D, giving both prototype test results and computational studies of beam interaction.  
 
THP048 Band Gap Structures of PBG and Rod-loaded Cavities damping, lattice, klystron, quadrupole 688
 
  • D. Yu, A. Smirnov, R. Yi
    DULY Research Inc., Rancho Palos Verdes, California
  The band-gap structures for rod loaded (RL) and photonic band gap (PBG) cavities are calculated with 2D and 3D frequency domain codes. It is shown that an RL cavity with a single circle of rods can exhibit similar behavior as a conventional single-defect PBG cavity. A systematic method of computing the unloaded Q factor using SUPERFISH has been implemented. Results are compared with GdfidL and Gd1 calculations.  
 
THP070 Study of BSNS RFQ Design rfq, coupling, simulation, quadrupole 746
 
  • H. F. Ouyang, S. Fu
    IHEP Beijing, Beijing
  A new 324MHz RFQ used for the project of Beijing Spallation Neutron Source (BSNS) is being designed. The designed injection and output energy are 50keV, 3.0MeV, respectively. The designed pulsed current is 40mA though the required current of BSNS at its first stage is only 20mA. The pulsed width is 420 s with a 50% chopping ratio and repetition rate is 25Hz. The transverse structure of BSNS RFQ will be basically the same as the former RFQ used for ADS, but the length of 3.62m is shorter comparing to the length of 4.75m of the former. The beam dynamics design and the RF structure design of the RFQ will be presented in this paper.  
 
THP084 Design of an 8-Gev H- Transport and Multiturn Injection System injection, linac, lattice, proton 779
 
  • D. E. Johnson
    Fermilab, Batavia, Illinois
  The baseline design of the transport and multiturn injection of 8 GeV H- to the FNAL Main Injector from a proposed 8 GeV superconducting linac will be discussed.