Author: Charles, T.K.
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MOPMF034 Layout and Performance of the FCC-ee Pre-Injector Chain 169
 
  • S. Ogur, T.K. Charles, K. Oide, Y. Papaphilippou, L. Rinolfi, F. Zimmermann
    CERN, Geneva, Switzerland
  • A.M. Barnyakov, A.E. Levichev, P.V. Martyshkin, D.A. Nikiforov
    BINP SB RAS, Novosibirsk, Russia
  • I. Chaikovska, R. Chehab
    LAL, Orsay, France
  • K. Furukawa, N. Iida, T. Kamitani, F. Miyahara
    KEK, Ibaraki, Japan
  • E.V. Ozcan
    Bogazici University, Bebek / Istanbul, Turkey
  • S.M. Polozov
    MEPhI, Moscow, Russia
 
  The Future Circular e+e Collider pre-injector chain consists of a 6 GeV S-Band linac, a damping ring at 1.54 GeV and pre-booster ring to reach 20 GeV for injection to the main booster. The electron and positron beams use the same accelerator chain alternatively. The e+ beam is generated from a novel low level RF-gun providing 6.5 nC charge at 11 MeV with 0.5 micron geometric emittance. The e+ beam is produced by the impact of a 4.46 GeV e- beam onto a hybrid target, accelerated in the linac up to 1.54 GeV, and injected to the damping ring for emittance cooling. Simulations on the performance of the DR are presented for reaching the required equilibrium emittances at the required damping time. As an alternative option, a 20 GeV linac is considered utilising C-Band cavities and simulations studies have been undertaken regarding the beam transport and transmission efficiency up to that energy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF034  
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MOPMF057 FCC-ee Dynamic Aperture Studies and Frequency Map Analysis 244
 
  • T. Tydecks, S. Aumon, T.K. Charles, B. Härer, B.J. Holzer, K. Oide, Y. Papaphilippou, J. Wenninger
    CERN, Geneva, Switzerland
 
  The FCC-ee Lepton Collider will provide e+e collisions in the beam energy range of 45.6 GeV to 182.5 GeV. FCC-ee will be a precision measurement tool for Z, W, H and t physics with expected luminosities of 2.07× 1036 cm-2 s-1 at the Z-pole and 1.3 × 1034 cm-2 s-1 at the tt- threshold. In order to achieve the foreseen luminosities, a vertical β* of 1 mm to 2 mm is mandatory. Dynamic aperture and frequency map analysis for the 97.75 km machine with such a squeezed accelerator optics are studied. Furthermore, effects of machine misalignments on dynamic and momentum aperture are presented and estimations for the required tolerances are given  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF057  
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WEYGBE2 Applications of Caustic Methods to Longitudinal Phase Space Manipulation 1790
 
  • T.K. Charles
    The University of Melbourne, Melbourne, Victoria, Australia
  • T.K. Charles
    CERN, Geneva, Switzerland
  • D. Douglas
    JLab, Newport News, Virginia, USA
  • P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Longitudinal phase space management is a key feature of recirculating machines. Careful consideration of the longitudinal matching is required not only in order to ensure a high peak current, low energy spread bunch is delivered to the FEL but also to support the deceleration and energy recovery of the spent beam. In a similar manner, longitudinal phase space manipulation can be utilised for pulse shaping in bunch compression, to minimise the influence of CSR-induced emittance growth. In this paper, we present a method for longitudinal phase space matching based upon the avoidance of electron trajectory caustics. Through considering the conditions under which caustics will form, we generate exclusion plots identifying the viable parameter space at numerous positions through beam acceleration and energy recovery. The result is a method for selecting the linear momentum compaction and the higher-order momentum compaction to satisfy the non-caustic condition whilst achieving the bunch compression or lengthening as required.  
slides icon Slides WEYGBE2 [6.296 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBE2  
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THPAF037 Bunch Compression and Turnaround Loops Design in the FCC-ee Injector Complex 3044
 
  • T.K. Charles, F. Zimmermann
    CERN, Geneva, Switzerland
  • M.J. Boland
    CLS, Saskatoon, Saskatchewan, Canada
  • K. Oide
    KEK, Ibaraki, Japan
 
  The Future Circular e+e Collider (FCC-ee) requires two 180-degree turnaround loops to transport the positron beam from the damping ring to the lower energy section of the linac. In addition bunch compression is required to reduce the RMS bunch length from 5 mm to 0.5 mm, prior to injection into the linac. A dogleg bunch compressor comprised of two triple bend achromat (TBAs) can achieve this compression. Sextupole magnets are incorporated into the bunch compressor design for chromaticity correction as well as optimisation of the second-order longitudinal dispersion, T566, and to linearize the longitudinal phase space distribution. In this paper we present the design of the transport line and the bunch compressor. Measures to limit emittance growth due to coherent synchrotron radiation (CSR) are also discussed, because despite the relatively long bunch length, the large degree of bending required introduces cause for consideration of CSR.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF037  
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THPMK106 Architectural Considerations for Recirculated and Energy-Recovered Hard XFEL Drivers 4560
 
  • D. Douglas, S.V. Benson, T. Powers, Y. Roblin, T. Satogata, C. Tennant
    JLab, Newport News, Virginia, USA
  • D. Angal-Kalinin, N. Thompson, A.E. Wheelhouse, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • T.K. Charles
    CERN, Geneva, Switzerland
  • R.C. York
    FRIB, East Lansing, Michigan, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A confluence of events motivates discussion of design options for hard XFEL driver accelerators. Firstly, multiple superconducting radio-frequency (SRF) driven systems are now online (European XFEL), in construction (LCLS-II), or in design (MARIE); these provide increasing evidence of the transformational potential they offer for fundamental science with its concomitant benefits. Secondly, operation of 12 GeV CEBAF* validates use of recirculation in high energy SRF linacs. Thirdly, advances in the analysis and control of effects such as coherent synchrotron radiation (CSR) and the microbunching instability (uBI) have been recently achieved. Collectively, these developments offer insights providing extended facility science reach, reduced costs, multiplicity (i.e., support of numerous FELs operating over a range of wavelengths), and enhanced scalability and upgradability (to higher powers and energies). We will discuss the relationship amongst the various threads, and indicate how they inform design choices for the system architecture of an option for the UK-XFEL** - that of a staged multi-user X-ray FEL and nuclear physics facility based on a multi-pass recirculating SRF CW linac.
*M. Spata, "12 GeV CEBAF Initial Operations and Challenges", these proceedings.
**P. Williams et al., Proc. FLS2018, Shanghai, China (March 2018).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK106  
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