Author: Bartnik, A.C.
Paper Title Page
TUYGBE2 CBETA, the 4-Turn ERL with SRF and Single Return Loop 635
 
  • G.H. Hoffstaetter, N. Banerjee, J. Barley, A.C. Bartnik, I.V. Bazarov, D.C. Burke, J.A. Crittenden, L. Cultrera, J. Dobbins, S.J. Full, F. Furuta, R.E. Gallagher, M. Ge, C.M. Gulliford, B.K. Heltsley, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, W. Lou, C.E. Mayes, J.R. Patterson, P. Quigley, D.M. Sabol, D. Sagan, J. Sears, C.H. Shore, E.N. Smith, K.W. Smolenski, V. Veshcherevich, D. Widger
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg, S.J. Brooks, C. Liu, G.J. Mahler, F. Méot, R.J. Michnoff, M.G. Minty, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, H. Witte
    BNL, Upton, Long Island, New York, USA
  • D. Douglas
    JLab, Newport News, Virginia, USA
  • J.K. Jones
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • D. Jusic
    Cornell University, Ithaca, New York, USA
  • D.J. Kelliher
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • B.C. Kuske, M. McAteer, J. Völker
    HZB, Berlin, Germany
 
  Funding: Supported by NSF award DMR-0807731, DOE grant DE-AC02-76SF00515, and NYSERDA.
A collaboration between Cornell University and Brookhaven National Laboratory has designed and is constructing CBETA, the Cornell-BNL ERL Test Accelerator on the Cornell campus. The ERL technology that has been prototyped at Cornell for many years is being used for this new accelerator, including a DC electron source and an SRF injector Linac with world-record current and normalized brightness in a bunch train, a high-current linac cryomodule optimized for ERLs, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams. BNL has designed multi-turn ERLs for several purpose, dominantly for the electron beam of eRHIC, its Electron Ion Collider (EIC) project and for the associated fast electron cooling system. Also in JLEIC, the EIC designed at JLAB, an ERL is envisioned to be used for electron cooling. The number of transport lines in an ERL is minimized by using return arcs that are comprised of a Fixed Field Alternating-gradient (FFA) design. This technique will be tested in CBETA, which has a single return for the 4-beam energies with strongly-focusing permanent magnets of Halbach type. The high-brightness beam with 150~MeV and up to 40~mA will have applications beyond accelerator research, in industry, in nuclear physics, and in X-ray science. Low current electron beam has already been sent through the most relevant parts of CBETA, from the DC gun through both cryomodules, through one of the 8 similar separator lines, and through one of the 27 similar FFA structures. Further construction is envisioned to lead to a commissioning start for the full system early in 2019.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBE2  
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TUPML028 Photocathodes R&D for High Brightness and Highly Polarized Electron Beams at Cornell University 1601
 
  • L. Cultrera, J. Bae, A.C. Bartnik, I.V. Bazarov, R. Doane, A. Galdi, C.M. Gulliford, W. H. Li, J.M. Maxson, S.A. McBride, T.P. Moore, C. M. Pierce, C. Xu
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Cornell University is a leader in the development of photocathode materials for the production of high brightness electron beam sources for applications in large scale accelerators and small scale electron scattering experiments. During the last year we have also included Mott polarimetry to investigate long lifetime spin-polarized photocathodes materials. Another thrust of our laboratory is the exploration of ultra low emittance photocathodes at cryogenic temperatures, for which we are building a novel LHe cryogenic electron source. We will review updates from our lab across each of these areas.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML028  
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WEPAF019 Fast Readout Algorithm for Cylindrical Beam Position Monitors Providing Good Accuracy for Particle Bunches with Large Offsets 1864
 
  • P. Thieberger, D.M. Gassner, R.L. Hulsart, R.J. Michnoff, T.A. Miller, M.G. Minty, Z. Sorrell
    BNL, Upton, Long Island, New York, USA
  • A.C. Bartnik
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work was supported by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the US Department of Energy.
A simple, analytically correct algorithm is developed for calculating 'pencil' beam coordinates using the signals from an ideal cylindrical beam position monitor (BPM) with four pickup electrodes (PUEs) of infinitesimal widths. The algorithm is then applied to simulations of realistic BPMs with finite width PUEs. Surprisingly small deviations are found. Simple empirically determined correction terms reduce the deviations even further. Finally, the algorithm is used to study the impact of beam-size upon the precision of BPMs in the non-linear region. As an example of the data acquisition speed advantage, a FPGA-based BPM readout implementation of the new algorithm has been developed and characterized
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF019  
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THPAF019 Initial Performance of the Magnet System in the Splitter/Combiner Section of the Cornell-Brookhaven Energy-Recovery Linac Test Accelerator 2986
 
  • J.A. Crittenden, A.C. Bartnik, R.M. Bass, D.C. Burke, J. Dobbins, C.M. Gulliford, Y. Li, D. Sagan, K.W. Smolenski, Turco, J. Turco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg
    BNL, Upton, Long Island, New York, USA
  • D. Jusic
    Cornell University, Ithaca, New York, USA
 
  Funding: This work is supported by NSF award DMR-0807731, DOE grant DE-AC02- 76SF00515, and New York State Energy Research and Development Authority.
The Cornell-Brookhaven Energy-recovery Linac Test Accelerator is a four-pass, 150-MeV electron accelerator with a six-cell 1.3 GHz superconducting-RF linear accelerator and a fixed-field alternating-gradient (FFAG) return loop made up of Halbach-style quadrupole magnets. The optics matching between the linear accelerator and the return loop is achieved with a conventional magnet system comprised of 50 dipole magnets and 64 quadrupole magnets in four beamlines at each end of the linac. The 42-, 78-, 114- and 150-MeV electron beams are separated into independent vacuum chambers in order to allow for the path-length adjustment required by energy recovery. We report on the first beam tests of the initial installation of the splitter/combiner section at the exit of the linac. The vacuum system of the 42-MeV S1 line was installed during the first week of April. Nine dipole and four quadrupole magnets were installed and surveyed into position the following week, and the water cooling system was commissioned. A 6-MeV beam passed through the line on April~11 with no need for adjusting pre-set magnet excitation currents. One week later, time-of-flight measurements were used to calibrate and phase the individual superconducting RF cavities. The S1 magnet settings were then scaled up to achieve 5-cavity, 42-MeV operation through the first nine FFAG permanent-magnet quadrupoles. This initial Fractional Arc Test will conclude on May 18, when the installation of the remaining seven splitter/combiner lines and the return loop will begin. CBETA operations are scheduled to begin in early 2019.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF019  
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THPAF021 Start to End Simulation of the CBETA Energy Recovery Linac 2993
 
  • W. Lou, A.C. Bartnik, J.A. Crittenden, C.M. Gulliford, G.H. Hoffstaetter, D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg, S.J. Brooks, F. Méot, D. Trbojevic, N. Tsoupas
    BNL, Upton, Long Island, New York, USA
  • C.E. Mayes
    SLAC, Menlo Park, California, USA
 
  Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
CBETA is an energy recovery linac accelerating from 6 MeV to 150 MeV in four linac passes, using a single return line accepting all energies from 42 MeV to 150 MeV. We simulate a 6-dimensional particle distribution from the injector through the end of the dump line. Space charge forces are taken into account at the low energy stages. We compare results using field maps to those using simpler magnet models. We introduce random and systematic magnet errors to the lattice, apply an orbit correction algorithm, and study the impact on the beam distribution.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF021  
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THPAF023 The Beam Optics of the FFAG Cell of the CBETA ERL Accelerator 3000
 
  • W. Lou, A.C. Bartnik, J.A. Crittenden, C.M. Gulliford, G.H. Hoffstaetter, D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg, S.J. Brooks, F. Méot, D. Trbojevic, N. Tsoupas
    BNL, Upton, Long Island, New York, USA
  • C.E. Mayes
    SLAC, Menlo Park, California, USA
 
  Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Cornell-Brookhaven Energy Recovery Linac Test Accelerator now under construction will accelerate electrons from 6 MeV to 150 MeV in four linac passes, using a single return line accepting all energies from 42 to 150 MeV. We describe the optical design of the machine, with emphasis on recent updates. We explain how we choose parameters for the wide energy acceptance return arc, taking into account 3D field maps generated from magnet designs. We give the final machine parameters resulting from iterations between desired lattice properties and magnet design. We modified the optics to improve the periodicity of the return arc near its ends and to create adequate space for vacuum hardware. The return arc is connected to the linac with splitter lines that serve to match the optics for each beam energy. We describe how matching conditions were chosen for the splitter lines and how we use them to control longitudinal motion. We simulate the injection and low energy extraction systems including space charge effects, matching the beam properties to the optical parameters of the rest of the machine.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF023  
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