Keyword: FEL
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MOZD2 Preliminary Study of a High Gain THz FEL in a Recirculating Cavity electron, radiation, undulator, GUI 30
  • A.C. Fisher, P. Musumeci
    UCLA, Los Angeles, California, USA
  The THz gap is a region of the electromagnetic spectrum where high average and peak power radiation sources are scarce while at the same time scientific and industrial applications are growing in demand. Free-electron laser coupling in a magnetic undulator is one of the best options for radiation generation in this frequency range, but slippage effects require the use of relatively long and low current electron bunches to drive the THz FEL, limiting amplification gain and output peak power. Here we use a circular waveguide in a 0.96 m strongly tapered helical undulator to match the radiation and e-beam velocities, allowing resonant energy extraction from an ultrashort 200 pC 5.5 MeV electron beam over an extended distance. E-beam energy measurements, supported by energy and spectral measurement of the THz FEL radiation, indicate an average energy efficiency of ~ 10%, with some particles losing > 20% of their initial kinetic energy.  
slides icon Slides MOZD2 [7.005 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZD2  
About • Received ※ 04 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 13 August 2022
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MOZD5 ERL-Based Compact X-Ray FEL electron, emittance, optics, laser 37
  • F. Lin, V.S. Morozov
    ORNL RAD, Oak Ridge, Tennessee, USA
  • J. Guo, Y. Zhang
    JLab, Newport News, Virginia, USA
  Funding: Work supported by UT-Battelle, LLC, under contract DE-AC05-00OR22725, and by Jefferson Science Associates, LLC, under contract DE-AC05-06OR23177
We propose to develop an energy-recovery-linac (ERL)-based X-ray free-electron laser (XFEL). Taking advantage of the demonstrated high-efficiency energy recovery of the beam power in the ERL, the proposed concept offers the following benefits: i) recirculating the electron beam through high-gradient superconducting RF (SRF) cavities shortens the linac, ii) energy recovery in the SRF linac saves the klystron power and reduces the beam dump power, iii) the high average beam power produces a high average photon brightness. In addition, such a concept has the capability of delivering optimized high-brightness CW X-ray FEL performance at different energies with simultaneous multipole sources. In this paper, we will present the preliminary results on the study of feasibility, optics design and parameter optimization of such a device.
slides icon Slides MOZD5 [2.870 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZD5  
About • Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 04 August 2022 — Issue date ※ 11 September 2022
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MOPA34 Noise in Intense Electron Bunches electron, laser, radiation, experiment 128
  • S. Nagaitsev, D.R. Broemmelsiek, J.D. Jarvis, A.H. Lumpkin, J. Ruan, G.W. Saewert, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  • Z. Huang, G. Stupakov
    SLAC, Menlo Park, California, USA
  • Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  We report on our investigations into density fluctuations in electron bunches. Noise and density fluctuations in relativistic electron bunches, accelerated in a linac, are of critical importance to various Coherent Electron Cooling (CEC) concepts as well as to free-electron lasers (FELs). For CEC, the beam noise results in additional diffusion that counteracts cooling. In SASE FELs, a microwave instability starts from the initial noise in the beam and eventually leads to the beam microbunching yielding coherent radiation, and the initial noise in the FEL bandwidth plays a useful role. In seeded FELs, in contrast, such noise interferes with the seed signal, so that reducing noise at the initial seed wavelength would lower the seed laser power requirement. Status of the project will be presented.  
poster icon Poster MOPA34 [0.638 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA34  
About • Received ※ 10 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 14 August 2022 — Issue date ※ 24 August 2022
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TUPA32 SCU Ends Configured as Phase Shifter undulator, simulation, electron, quadrupole 420
  • M.F. Qian
    ANL, Lemont, Illinois, USA
  Funding: Work supported by LDRD funding from Argonne National Laboratory, provided by the Director, Office of Science, of the U.S. DOE under Contract No. DE-AC02-06CH11357.
Dipole correctors and phase shifters are usually needed in the interspace of a permanent magnet (PM)-based undulator array for purposes of beam steering and phase matching when the field strength is changing. Unlike the PM-based undulators, the superconducting undulator (SCU) can change its end field with the help of varying currents in the end coils. By setting the end coil currents the beam-steering and the phase-matching could be realized, thus eliminating the need for standalone correctors and phase shifters, saving the interspace as well as reducing the mechanical complexity of an undulator array. We developed a procedure for determining the SCU end coil currents and verified it by numerical simulations. The procedure as well as the simulation results are described in this paper.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA32  
About • Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 07 September 2022
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TUPA33 Magnetic Field Calculation of Superconducting Undulators for FEL Using Maxwell 3D undulator, electron, wiggler, laser 423
  • Y. Shiroyanagi, Y. Ivanyushenkov, M. Kasa
    ANL, Lemont, Illinois, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
An ANL-SLAC collaboration is working on design of a planar superconducting undulator (SCU) demonstrator for a FEL. As a part of this project, a SCU magnet prototype is planned to be built and tested. A planar SCU magnet consisting of a 1.0-m-long segment is being designed. Although OPERA is a standard tool for magnetic field calculation, ANSYS Maxwell 3D can also be used for a large and complex geometry. An ANSYS calculated magnetic field was benchmarked with the measured field profile of existing SCUs. This paper presents calculations of magnetic field and field integrals of 0.5-m-long and 1.0-m-long planar SCUs with a new end correction scheme. Then, an external phase shifter is also incorporated into the model. A cross-talk between a phase shifter and SCU magnetic structures is also presented.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA33  
About • Received ※ 02 August 2022 — Revised ※ 03 August 2022 — Accepted ※ 05 August 2022 — Issue date ※ 25 August 2022
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TUPA38 Sublinear Intensity Response of Cerium-Doped Yttrium Aluminium Garnet Screen with Charge electron, booster, linac, storage-ring 437
  • K.P. Wootton, A.H. Lumpkin
    ANL, Lemont, Illinois, USA
  Funding: This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
Swap-out injection to the Advanced Photon Source Upgrade storage ring necessitates the injection of ~17 nC electron bunches at 6 GeV. To aid with machine tune-up and to measure the beam size, diagnostic imaging screens are envisaged at several locations in the beam transport line from the booster synchrotron to the storage ring. As such, it is important to determine whether the response of these screens to charge is linear. In the present work, we examine the effect of sublinear intensity quenching of a Cerium-doped Yttrium-Aluminium-Garnet scintillator screen. A 1.3 megapixel FLIR BlackFly monochrome digital camera was used to image the beam at the scintillator. At 7 GeV beam energy, over the charge densities investigated (<10 fC um-2), an approximately 10 % reduction of the imaging intensity due to quenching of the scintillator was observed.
poster icon Poster TUPA38 [0.557 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA38  
About • Received ※ 02 August 2022 — Accepted ※ 03 August 2022 — Issue date ※ 09 August 2022  
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TUPA72 Comparison Study on First Bunch Compressor Schemes by Conventional and Double C-Chicane for MaRIE XFEL dipole, emittance, electron, radiation 496
  • H. Xu, P.M. Anisimov, L.D. Duffy, Q.R. Marksteiner
    LANL, Los Alamos, New Mexico, USA
  Funding: Laboratory Directed Research and Development program of Los Alamos National Laboratory, project number 20200287ER.
We report our comparison study on the first stage electron bunch compression schemes at 750 MeV using a conventional and a double C-chicane for the X-ray free electron laser (XFEL) under development for the Matter-Radiation Interactions in Extremes (MaRIE) initiative at Los Alamos National Laboratory. Compared to the performance of the conventional C-chicane bunch compressor, the double C-chicane scheme exhibits the capability of utilizing the transverse momentum shift induced by the coherent synchrotron radiation in the second C-chicane to compensate that generated in the first C-chicane, resulting in a compressed electron bunch with minimized transverse momentum shift along the beam. It is also found that the double C-chicane scheme can be designed to significantly better preserve the beam emittance in the course of the bunch compression. This is particularly beneficial for the MaRIE XFEL whose lasing performance critically depends on the preservation of the ultralow beam emittance.
poster icon Poster TUPA72 [1.339 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA72  
About • Received ※ 01 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 15 August 2022  
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THYD6 Arrival Time and Energy Jitter Effects on the Performance of X-Ray Free Electron Laser Oscillator cavity, electron, laser, radiation 866
  • G. Tiwari
    BNL, Upton, New York, USA
  • K.-J. Kim, R.R. Lindberg
    ANL, Lemont, Illinois, USA
  • K.-J. Kim
    University of Chicago, Chicago, Illinois, USA
  Funding: U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357.
We report on the effects of electron beam arrival time and energy jitter on the power level and the fluctuations of the output of an X-ray FEL oscillator (XFELO). For this study, we apply the FEL driven paraxial resonator model of XFELO along with an analytical reflectivity profile to mimic the phase shift and spectral filtering effects of Bragg-crystals. The thresholds for acceptable timing jitters and energy jitters are determined in terms of the fluctuations of the steady-state power output. We explore potential ways to mitigate the power output fluctuations in the presence of unavoidable electron beam jitters.
slides icon Slides THYD6 [1.935 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYD6  
About • Received ※ 01 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 03 October 2022
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THYE3 Superconducting Undulators and Cryomodules for X-ray Free-Electron Lasers undulator, electron, alignment, quadrupole 870
  • D.C. Nguyen, G.J. Bouchard, B.M. Dunham, G.L. Gassner, Z. Huang, E.M. Kraft, P. Krejcik, M.A. Montironi, H.-D. Nuhn, T.O. Raubenheimer, Z.R. Wolf, Z. Zhang
    SLAC, Menlo Park, California, USA
  • J.M. Byrd, J.D. Fuerst, E. Gluskin, Y. Ivanyushenkov, M. Kasa, E.R. Moog, M.F. Qian, Y. Shiroyanagi
    ANL, Lemont, Illinois, USA
  Funding: Work supported by the US DOE Office of Science, Basic Energy Sciences, Office of Accelerator and Detector Research (Manager: Dr. Eliane Lessner).
We present connectable designs of superconducting undulators (SCU) and cryomodules (CM) based on previous SCU and CM designs at Argonne National Lab. The new SCU and CM designs will allow us to connect one CM to the next to form a contiguous line of SCUs with no breaks between the cryomodules. The SCU design will have correctors and phase shifters integrated into the main SCU magnet core, as well as external corrector magnets for trajectory corrections. There will also be a cryogenic magnetic quadrupole and a cold RF beam position monitor (BPM) integrated in the SCU CM. In addition to providing the usual FODO transverse focusing, the quadrupole and BPM will be used for the beam-based alignment technique that is critical for X-ray FEL operation. In this paper, we will present the conceptual design of the new SCU CM as well as results of FEL simulations using the SCUs as afterburners for the LCLS hard X-ray undulators.
slides icon Slides THYE3 [2.657 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYE3  
About • Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 16 August 2022
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