Keyword: optics
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MO3A02 Achievement of Small Beam Size at ATF2 Beamline sextupole, wakefield, laser, simulation 27
 
  • T. Okugi
    KEK, Ibaraki, Japan
 
  The beam commissioning of the ATF2 facility at KEK - a 1.3 GeV prototype of the compact local chromaticity correction final focus system for the linear collider - achieved 44nm beam size, very close to ideal expected size of 37nm, by developing various knobs and improving the performances of the interferometric Shintake monitor at the same time. These results have opened the way to reliable and predictable operation of the linear collider.  
slides icon Slides MO3A02 [3.495 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO3A02  
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MOPRC008 Dispersion Free and Dispersion Target Steering Experience at CTF3 linac, target, quadrupole, dipole 83
 
  • D. Gamba, R. Corsini, T. Persson, P.K. Skowroński, F. Tecker
    CERN, Geneva, Switzerland
  • P. Burrows
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  • P. Burrows
    JAI, Oxford, United Kingdom
 
  One of the goals of the CLIC Test Facility (CTF3) at CERN is to demonstrate the feasibility of the CLIC Drive Beam recombination, which takes place in the Drive Beam Recombination Complex (DBRC). The tight geometry of the DBRC together with its strong optics and the high energy-spread of the beam require a careful control of the beam size along the different sections of the DBRC. One of the main contribution to beam size is the dispersion. If uncontrolled, dispersion leads to fast increase of the beam size, hence it may affect the beam current stability of the combined beam. A tool has been implemented at CTF3 to measure and correct dispersion during and after the setup of the machine. Dispersion Free Steering (DFS) has been applied in the upstream drive beam LINAC, while Dispersion Target Steering (DTS) has been used in the rings of the DBRC. In the LINAC the weak optics and the wide dynamic aperture of the beamline allow a straightforward correction. In the DBRC the aperture is tighter, and the strong optics produce non-linear dispersion which one needs to take into account. A general overview of current status and future plans in controlling dispersion at CTF3 will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC008  
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MOPRC009 Simulating Apertures in the Uniform Equivalent Beam Model simulation, quadrupole, space-charge, software 87
 
  • G.H. Gillespie
    G.H. Gillespie Associates, Inc., Del Mar, California, USA
 
  The uniform equivalent beam model is useful for simulating particle beam envelopes. Beam root-mean-square (rms) sizes, divergences, and emittances of an equivalent uniform beam approximate well the rms properties of more realistic beam distributions, even in the presence of space charge. Envelope simulation codes for high current beams using the model, such as TRACE 3-D, are central to particle optics design. However, the modeling of apertures has required multi-particle simulation codes. Multi-particle codes do not typically have the fitting and optimization capabilities common to envelope codes, so the evaluation of aperture effects is often a secondary study that may result in further design iteration. To incorporate aperture effects into the optics design at the start, a method has been developed for simulating apertures in the context of a uniform equivalent beam. The method is described and its TRACE 3-D implementation is outlined. Comparisons with multi-particle simulations are used to validate the method and examine regions of applicability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC009  
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THOP04 Measurements of the Beam Break-Up Threshold Current at the Recirculating Electron Accelerator S-DALINAC linac, electron, recirculation, HOM 751
 
  • T. Kürzeder, M. Arnold, L.E. Jürgensen, J. Pforr, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    IKP, Mainz, Germany
 
  Funding: *Supported by the German Federal Ministry for Education and Research (BMBF) under Grant No. 05K13RDA.
Linear accelerators, in particular those with a recirculating design and superconducting cavities, have to deal with the problem of Beam Break-Up (BBU). This instability can limit the maximum beam current in such accelerators. Knowing the effectiveness of prevention strategies is of great interest especially for future accelerators like energy recovery linacs (ERL) which aim for high beam currents. One option is to optimize the cavities and higher order mode couplers of those machines. In addition one may adapt the beam line lattice for further suppressing BBU. The superconducting recirculating accelerator S-DALINAC at the Technische Universität Darmstadt provides electron beams in c.w. for nuclear physics experiments since 1991. As the SRF components were never optimized for higher order mode suppression the S-DALINAC suffers from BBU at relatively low beam currents of a few μA. While those currents are sufficient for most nuclear physics experiments we can investigate BBU with respect to the beam optics. We will report on first measurements of threshold currents at different beam energies of the S-DALINAC. The results of a first test to increase the BBU limit by using skew quadrupoles will be presented.
 
slides icon Slides THOP04 [1.473 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP04  
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FR1A01 Fast Envelope Tracking for Space Charge Dominated Injectors space-charge, linac, TRIUMF, GUI 1017
 
  • R.A. Baartman
    TRIUMF, Vancouver, Canada
 
  High brightness injectors are increasingly pushing against space charge effects. Usually, particle tracking codes such as ASTRA, GPT, or PARMELA are used to model these systems however these can be slow to use for detailed optimization. It becomes increasingly challenging in future projects such as LCLS-II where space charge effects are still significant after BC1 and BC2 at 250 and 1600 MeV respectively. This talk will describe an envelope tracking approach that compares well against the particle tracking codes and could facilitate much faster optimization.  
slides icon Slides FR1A01 [0.786 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-FR1A01  
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