Keyword: laser
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MOZD5 ERL-Based Compact X-Ray FEL electron, FEL, emittance, optics 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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MOZE3 Emittance Measurements and Simulations from an X-Band Short-Pulse Ultra-High Gradient Photoinjector emittance, gun, linac, simulation 45
  • G. Chen, D.S. Doran, C.-J. Jing, S.Y. Kim, W. Liu, W. Liu, P. Piot, J.G. Power, C. Whiteford, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  • C.-J. Jing, E.W. Knight, S.V. Kuzikov
    Euclid TechLabs, Solon, Ohio, USA
  • C.-J. Jing
    Euclid Beamlabs, Bolingbrook, USA
  • X. Lu, P. Piot, W.H. Tan
    Northern Illinois University, DeKalb, Illinois, USA
  Funding: This work is supported by the U.S. DOE, under award No. DE-SC0018656 to NIU, DOE SBIR grant No. DE-SC0018709 to Euclid Techlabs LLC, and contract No. DE-AC02-06CH11357 with ANL.
A program is under way at the Argonne Wakefield Accelerator facility, in collaboration with the Euclid Techlabs and Northern Illinois University (NIU), to develop a GeV/m scale photocathode gun, with the ultimate goal of demonstrating a high-brightness photoinjector beamline. The novel X-band photoemission gun (Xgun) is powered by high-power, short RF pulses, 9-ns (FWHM), which, in turn, are generated by the AWA drive beam. In a previous proof-of-principle experiment, an unprecedented 400~MV/m gradient on the photocathode surface* was demonstrated. In the current version of the experiment, we added a linac to the beamline to increase the total energy and gain experience tuning the beamline. In this paper, we report on the very first result of emittance measurement as well as several other beam parameters. This preliminary investigation has identified several factors to be improved on in order to achieve one of the ultimate goals; low emittance.
* W. H. Tan et al., "Demonstration of sub-GV/m Accelerating Field in a Photoemission Electron Gun Powered by Nanosecond X-Band Radiofrequency Pulses", 2022. arXiv:2203.11598v1
slides icon Slides MOZE3 [5.565 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZE3  
About • Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 14 August 2022
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MOPA13 Design of a Surrogate Model for MUED at BNL Using VSim, Elegant and HPC simulation, gun, electron, detector 72
  • S.I. Sosa Guitron, S. Biedron, T.B. Bolin
    UNM-ECE, Albuquerque, USA
  • S. Biedron
    Element Aero, Chicago, USA
  • S. Biedron
    UNM-ME, Albuquerque, New Mexico, USA
  Funding: U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Program of Electron and Scanning Probe Microscopes, award number DE-SC0021365.
The MeV Ultrafast Electron Diffraction (MUED) instrument at Brookhaven National Laboratory is a unique capability for material science. As part of a plan to make MUED a high-throughput user facility, we are exploring instrumentation developments based on Machine Learning (ML). We are developing a surrogate model of MUED that can be used to support control tasks. The surrogate model will be based on beam simulations that are benchmarked to experimental observations. We use VSim to model the beam dynamics of the radio-frequency gun and Elegant to transport the beam through the rest of the beam-line. We also use High Performance Computing resources from Argonne Leadership Computing Facility to generate the data for the surrogate model based on the original simulation as well as training the ML model.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA13  
About • Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 August 2022
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MOPA34 Noise in Intense Electron Bunches electron, radiation, FEL, 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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MOPA50 Integrated Photonics Structure Cathodes for Longitudinally Shaped Bunch Trains wakefield, cathode, emittance, simulation 160
  • S.J. Coleman, D.T. Abell, C.C. Hall
    RadiaSoft LLC, Boulder, Colorado, USA
  • R. Kapadia
    University of Southern California, Los Angeles, California, USA
  • S.S. Karkare
    Arizona State University, Tempe, USA
  • S.Y. Kim, P. Piot, J.F. Power
    ANL, Lemont, Illinois, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DOE DE-SC0021681
Compact, high-gradient structure wakefield accelerators can operate at improved efficiency using shaped electron beams, such as a high transformer ratio beam shape, to drive the wakes. These shapes have generally come from a photocathode gun followed by a transverse mask to imprint a desired shape on the transverse distribution, and then an emittance exchanger (EEX) to convert that transverse shape into a longitudinal distribution. This process discards some large fraction of the beam, limiting wall-plug efficiency as well as leaving a solid object in the path of the beam. In this paper, we present a proposed method of using integrated photonics structures to control the emission pattern on the cathode surface. This transverse pattern is then converted into a longitudinal pattern at the end of an EEX. This removes the need for the mask, preserving the total charge produced at the cathode surface. We present simulations of an experimental set-up to demonstrate this concept at the Argonne Wakefield Accelerator.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA50  
About • Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 26 August 2022 — Issue date ※ 03 October 2022
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MOPA78 Temporally-Shaped Ultraviolet Pulses for Tailored Bunch Generation at Argonne Wakefield Accelerator electron, controls, wakefield, cathode 222
  • T. Xu, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • S. Carbajo
    UCLA, Los Angeles, California, USA
  • S. Carbajo, R.A. Lemons
    SLAC, Menlo Park, California, USA
  • P. Piot
    ANL, Lemont, Illinois, USA
  Photocathode laser shaping is an appealing technique to generate tailored electron bunches due to its versatility and simplicity. Most photocathodes require photon energies exceeding the nominal photon energy produced by the lasing medium. A common setup consists of an infrared (IR) laser system with nonlinear frequency conversion to the ultraviolet (UV). In this work, we present the numerical modeling of a temporal shaping technique capable of producing electron bunches with linearly-ramped current profiles for application to collinear wakefield accelerators. Specifically, we show that controlling higher-order dispersion terms associated with the IR pulse provides some control over the UV temporal shape. Beam dynamics simulation of an electron-bunch shaping experiment at the Argonne Wakefield Accelerator is presented.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA78  
About • Received ※ 01 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 31 August 2022
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TUXD4 Analysis Methods for Electron Radiography Based on Laser-Plasma Accelerators electron, plasma, target, experiment 274
  • G.M. Bruhaug, G.W. Collins, H.G. Rinderknecht, J.R. Rygg, J.L. Shaw, M.S. Wei
    LLE, Rochester, New York, USA
  • M.S. Freeman, F.E. Merrill, L.P. Neukirch, C. Wilde
    LANL, Los Alamos, New Mexico, USA
  Funding: DOE National Nuclear Security Administration under Award Number DE-NA0003856 DOE under Awards DE-SC00215057 University of Rochester New York State Energy Research and Development Authority
Analysis methods are presented for determining the res-olution of both contact and projected electron radiography based on a laser-plasma accelerator. A means to determine the field strength of the electric/magnetic fields generated when a laser is incident on an object of interest is also outlined. Broad radiography results are reported and future plans for the diagnostic technique are outlined.
slides icon Slides TUXD4 [12.157 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUXD4  
About • Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 03 September 2022
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TUYD4 Towards High Brightness from Plasmon-Enhanced Photoemitters cathode, electron, interface, emittance 285
  • C.M. Pierce, I.V. Bazarov, J.M. Maxson
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • D.B. Durham, D. Filippetto, F. Riminucci
    LBNL, Berkeley, USA
  • A.H. Kachwala, S.S. Karkare
    Arizona State University, Tempe, USA
  • A. Minor
    UC Berkeley, Berkeley, California, USA
  Funding: This work is supported by DOE BES Contract No. DE-AC02-05CH11231. C.P. acknowledges NSF Award PHY-1549132 (CBB) and the US DOE SCGSR program. DD was supported by NSF Grant No. DMR-1548924 (STROBE).
Plasmonic cathodes, whose nanoscale features may locally enhance optical energy from the driving laser trapped at the vacuum interface, have emerged as a promising technology for improving the brightness of metal cathodes. A six orders of magnitude improvement [1] in the non-linear yield of metals has been experimentally demonstrated through this type of nanopatterning. Further, nanoscale lens structures may focus light below its free-space wavelength offering multiphoton photoemission from a region near 10 times smaller [2] than that achievable in typical photoinjectors. In this proceeding, we report on our efforts to characterize the brightness of two plasmonic cathode concepts: a spiral lens and a nanogroove array. We demonstrate an ability to engineer and fabricate nanoscale patterned cathodes by comparing their optical properties with those computed with a finite difference time domain (FDTD) code. The emittance and nonlinear yield of the cathodes are measured under ultrafast laser irradiation. Finally, prospects of this technology for the control and acceleration of charged particle beams are discussed.
[1] Polyakov, A., et al. (2013). Physical Review Letters, 110(7), 076802.
[2] Durham, D. B., et al. (2019). Physical Review Applied, 12(5), 054057.
slides icon Slides TUYD4 [7.160 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD4  
About • Received ※ 05 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 13 September 2022
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TUYD5 Epitaxial Alkali-Antimonide Photocathodes on Lattice-matched Substrates cathode, ECR, electron, lattice 289
  • P. Saha, S.S. Karkare
    Arizona State University, Tempe, USA
  • E. Echeverria, A. Galdi, J.M. Maxson, C.A. Pennington
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • E.J. Montgomery, S. Poddar
    Euclid Beamlabs, Bolingbrook, USA
  Alkali-antimonides photocathodes, characterized by high quantum efficiency (QE) and low mean transverse energy (MTE) in the visible range of spectrum, are excellent candidates for electron sources to drive X-ray Free Electron Lasers (XFEL) and Ultrafast Electron Diffraction (UED). A key figure of merit for these applications is the electron beam brightness, which is inversely proportional to MTE. MTE can be limited by nanoscale surface roughness. Recently, we have demonstrated physically and chemically smooth Cs3Sb cathodes on Strontium Titanate (STO) substrates grown via co-deposition technique. Such flat cathodes could result from a more ordered growth. In this paper, we present RHEED data of co-deposited Cs3Sb cathodes on STO. Efforts to achieve epitaxial growth of Cs3Sb on STO are then demonstrated via RHEED. We find that films grown epitaxially on substrates like STO and SiC (previously used to achieve single crystalline Cs3Sb) exhibit QE higher than the polycrystalline Cs3Sb cathodes, by an order of magnitude below photoemission threshold. Given the larger QE, lower laser fluence could be used to extract high charge densities, thereby leading to enhanced beam brightness.  
slides icon Slides TUYD5 [2.088 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD5  
About • Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 07 September 2022
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TUYE1 Coulomb Crystals in Storage Rings for Quantum Information Science storage-ring, controls, rfq, operation 296
  • K.A. Brown
    BNL, Upton, New York, USA
  • A. Aslam, S. Biedron, T.B. Bolin, C. Gonzalez-Zacarias, S.I. Sosa Guitron
    UNM-ECE, Albuquerque, USA
  • B. Huang
    SBU, Stony Brook, USA
  • T.G. Robertazzi
    Stony Brook University, Stony Brook, New York, USA
  Quantum information science is a growing field that promises to take computing into a new age of higher performance and larger scale computing as well as being capable of solving problems classical computers are incapable of solving. The outstanding issue in practical quantum computing today is scaling up the system while maintaining interconnectivity of the qubits and low error rates in qubit operations to be able to implement error correction and fault-tolerant operations. Trapped ion qubits offer long coherence times that allow error correction. However, error correction algorithms require large numbers of qubits to work properly. We can potentially create many thousands (or more) of qubits with long coherence states in a storage ring. For example, a circular radio-frequency quadrupole, which acts as a large circular ion trap and could enable larger scale quantum computing. Such a Storage Ring Quantum Computer (SRQC) would be a scalable and fault tolerant quantum information system, composed of qubits with very long coherence lifetimes.  
slides icon Slides TUYE1 [8.834 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYE1  
About • Received ※ 17 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 11 August 2022
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TUPA33 Magnetic Field Calculation of Superconducting Undulators for FEL Using Maxwell 3D undulator, FEL, electron, wiggler 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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TUPA41 Applications of Machine Learning in Photo-Cathode Injectors electron, controls, cathode, network 441
  • A. Aslam
    UNM-ECE, Albuquerque, USA
  • M. Babzien
    BNL, Upton, New York, USA
  • S. Biedron
    Element Aero, Chicago, USA
  To configure a photoinjector to reproduce a given electron bunch with the desired characteristics, it is necessary to adjust the operating parameters with high precision. More or less, the fine tunability of the laser parameters are of extreme importance as we try to model further applications of the photoinjector. The laser pulse incident on the photocathode critically affects the electron bunch 3D phase space. Parameters such as the laser pulse transverse shape, total energy, and temporal profile must be controlled independently, any laser pulse variation over both short and long-time scales also requires correction. The ability to produce arbitrary laser intensity distributions enables better control of electron bunch transverse and longitudinal emittance by affecting the space-charge forces throughout the bunch. In an accelerator employing a photoinjector, electron optics in the beamline downstream are used to transport, manipulate, and characterize the electron bunch. The adjustment of the electron optics to achieve a desired electron bunch at the interaction point is a much better understood problem than laser adjustment, so this research emphasizes laser shaping.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA41  
About • Received ※ 30 July 2022 — Revised ※ 12 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 07 September 2022
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TUPA77 X-Band Harmonic Longitudinal Phase Space Linearization at the PEGASUS Photoinjector cavity, linac, electron, gun 508
  • P.E. Denham, P. Musumeci, A. Ody
    UCLA, Los Angeles, USA
  Due to the finite bunch length, photoemitted electron beams sample RF-nonlinearities that lead to energy-time correlations along the bunch temporal profile. This is an important effect for all applications where the projected energy spread is important. In particular, for time-resolved single shot electron microscopy, it is critical to keep the beam energy spread below 1·10-4 to avoid chromatic aberrations in the lenses. Higher harmonic RF cavities can be used to compensate for the RF-induced longitudinal phase space nonlinearities. Start-to-end simulations suggest that this type of compensation can reduce energy spread to the 1·10-5 level. This work is an experimental study of x-band harmonic linearization of a beam longitudinal phase space at the PEGASUS facility, including developing high-resolution spectrometer diagnostics to verify the scheme.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA77  
About • Received ※ 25 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 10 August 2022
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TUPA85 First Results from a Multileaf Collimator and Emittance Exchange Beamline wakefield, plasma, acceleration, vacuum 531
  • N. Majernik, G. Andonian, C.D. Lorch, W.J. Lynn, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • D.S. Doran, S.Y. Kim, P. Piot, J.G. Power, C. Whiteford, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  Funding: Department of Energy DE-SC0017648 and National Science Foundation PHY-1549132.
By shaping the transverse profile of a particle beam prior to an emittance exchange (EEX) beamline, drive and witness beams with variable current profiles and bunch spacing can be produced. Presently at AWA, this transverse shaping is accomplished with individually laser-cut tungsten masks, making the refinement of beam profiles a slow process. In contrast, a multileaf collimator (MLC) is a device that can selectively mask the profile of a beam using many independently actuated leaves. Since an MLC permits real-time adjustment of the beam shape, its use as a beam mask would permit much faster optimization in a manner highly synergistic with machine learning. Beam dynamics simulations have shown that such an approach is functionally equivalent to that offered by the laser cut masks. In this work, the construction and first results from a 40-leaf, UHV compatible MLC are discussed.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA85  
About • Received ※ 16 July 2022 — Revised ※ 02 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 12 August 2022
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TUPA86 Simulations of Nanoblade Cathode Emissions with Image Charge Trapping for Yield and Brightness Analyses electron, brightness, emittance, scattering 535
  • J.I. Mann, G.E. Lawler, J.B. Rosenzweig, B. Wang
    UCLA, Los Angeles, California, USA
  • T. Arias, J.K. Nangoi
    Cornell University, Ithaca, New York, USA
  • S.S. Karkare
    Arizona State University, Tempe, USA
  Funding: National Science Foundation Grant No. PHY-1549132
Laser-induced field emission from nanostructures as a means to create high brightness electron beams has been a continually growing topic of study. Experiments using nanoblade emitters have achieved peak fields upwards of 40 GV/m according to semi-classical analyses, begging further theoretical investigation. A recent paper has provided analytical reductions of the common semi-infinite Jellium system for pulsed incident lasers. We utilize these results to further understand the physics underlying electron rescattering-type emissions. We numerically evaluate this analytical solution to efficiently produce spectra and yield curves. The effect of space-charge trapping at emission may be simply included by directly modifying these spectra. Additionally, we use a self-consistent 1-D time-dependent Schrödinger equation with an image charge potential to study the same system as a more exact, but computationally costly, approach. With these results we may finally investigate the mean transverse energy and beam brightness at the cathode in these extreme regimes.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA86  
About • Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 03 September 2022
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WEXD6 Electron Cloud Measurements in Fermilab Booster electron, booster, simulation, proton 556
  • S.A.K. Wijethunga, J.S. Eldred, E. Pozdeyev, C.-Y. Tan
    Fermilab, Batavia, Illinois, USA
  Fermilab Booster synchrotron requires an intensity upgrade from 4.5×1012 to 6.5×1012 protons per pulse as a part of Fermilab’s Proton Improvement Plan-II (PIP-II). One of the factors which may limit the high-intensity performance is the fast transverse instabilities caused by electron cloud effects. According to the experience in the Recycler, the electron cloud gradually builds up over multiple turns in the combined function magnets and can reach final intensities orders of magnitude greater than in a pure dipole. Since the Booster synchrotron also incorporates combined function magnets, it is important to discover any existence of an electron cloud. And if it does, its effects on the PIP-II era Booster and whether mitigating techniques are required. As the first step, the presence or absence of the electron cloud was investigated using a gap technique. This paper presents experimental details and observations of the bunch-by-bunch tune shifts of beams with various bunch train structures at low and high intensities and simulation results conducted using PyECLOUD software.  
slides icon Slides WEXD6 [4.483 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEXD6  
About • Received ※ 02 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 21 August 2022 — Issue date ※ 09 September 2022
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WEZD1 ARDAP’s Perspective on Accelerator Technology R&D in the U.S. operation, electron, collider, controls 592
  • B.E. Carlsten, E.R. Colby, R.A. Marsh, M. White
    ARDAP, Washington, USA
  DOE operates several particle accelerator facilities and is planning several new forward-leaning accelerator facilities over the next decade or two. These new facilities will focus on discovery science research and fulfilling other core DOE missions. Near and mid-term examples include PIP-II and FACET-II (for High Energy Physics); LCLS-II, SNS-PPU, APS-U, and ALS-U (for Basic Energy Sciences); FRIB (for Nuclear Physics); NSTX-U and MPEX (for Fusion Energy Sciences); and Scorpius (for NNSA). Longer-term examples may include future colliders, the SNS-STS, LCLS-II HE, and EIC. In addition to domestic facilities, DOE’s Office of Science (SC) also contributes to several international efforts. Together, these new facilities constitute a multibillion-dollar construction and operations investment. To be successful, they will require advances in state-of-the-art accelerator technologies. They will also require the National Laboratories to procure a variety of accelerator components. This paper summarizes how DOE is working to address these upcoming R&D and accelerator component production needs through its new office of Accelerator R&D and Production (ARDAP).  
slides icon Slides WEZD1 [2.310 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD1  
About • Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 19 August 2022
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WEPA13 New Results at JLab Describing Operating Lifetime of GaAs Photo-guns gun, cathode, electron, experiment 644
  • M.W. Bruker, J.M. Grames, C. Hernandez-Garcia, M. Poelker, S. Zhang
    JLab, Newport News, Virginia, USA
  • V.M. Lizárraga-Rubio, C.A. Valerio-Lizárraga
    ECFM-UAS, Culiacan, Sinaloa, Mexico
  • J.T. Yoskowitz
    ODU, Norfolk, Virginia, USA
  Funding: This work is supported by U.S. Department of Energy under DE-AC05-06OR23177 and by Consejo Nacional de Ciencia y Tecnología and the Universidad Autonoma de Sinaloa under PRO_A1_022.
Polarized electrons from GaAs photocathodes have been key to some of the highest-impact results of the Jefferson Lab science program over the past 30 years. During this time, various studies have given insight into improving the operational lifetime of these photocathodes in DC high-voltage photo-guns while using lasers with spatial Gaussian profiles of typically 0.5 mm to 1 mm FWHM, cathode voltages of 100 kV to 130 kV, and a wide range of beam currents up to multiple mA. In this contribution, we show recent experimental data from a 100 kV to 180 kV setup and describe our progress at predicting the lifetime based on the calculable dynamics of ionized gas molecules inside the gun. These new experimental studies at Jefferson Lab are specifically aimed at exploring the ion damage of higher-voltage guns being built for injectors.
poster icon Poster WEPA13 [1.644 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA13  
About • Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 01 October 2022
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WEPA17 Improved Electrostatic Design of the Jefferson Lab 300 kV DC Photogun and the Minimization of Beam Deflection gun, cathode, electron, high-voltage 655
  • M.A. Mamun, D.B. Bullard, J.M. Grames, C. Hernandez-Garcia, G.A. Krafft, M. Poelker, R. Suleiman
    JLab, Newport News, Virginia, USA
  • J.R. Delayen, G.A. Krafft, G.G. Palacios Serrano, S.A.K. Wijethunga
    ODU, Norfolk, Virginia, USA
  Funding: This work is supported by the Department of Energy, under contract DE-AC05-06OR23177, JSA initiatives fund program, and the Laboratory Directed Research and Development program.
An electron beam with high bunch charge and high repetition rate is required for electron cooling of the ion beam to achieve the high luminosity required for the proposed electron-ion colliders. An improved design of the 300 kV DC high voltage photogun at Jefferson Lab was incorporated toward overcoming the beam loss and space charge current limitation experienced in the original design. To reach the bunch charge goal of ~ few nC within 75 ps bunches, the existing DC high voltage photogun electrodes and anode-cathode gap were modified to increase the longitudinal electric field (Ez) at the photocathode. The anode-cathode gap was reduced to increase the Ez at the photocathode, and the anode aperture was spatially shifted with respect to the beamline longitudinal axis to minimize the beam deflection introduced by the geometric asymmetry of the inverted insulator photogun. The electrostatic design and beam dynamics simulations were performed to determine the required modification. Beam-based measurement from the modified gun confirmed the reduction of the beam deflection, which is presented in this contribution.
poster icon Poster WEPA17 [2.973 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA17  
About • Received ※ 23 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 05 August 2022 — Issue date ※ 11 August 2022
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WEPA33 Laser Stripping for 1.3 GeV H Beam at the SNS injection, photon, emittance, experiment 702
  • T.V. Gorlov, A.V. Aleksandrov, S.M. Cousineau, Y. Liu, A.R. Oguz
    ORNL, Oak Ridge, Tennessee, USA
  • M.J. Kay
    UTK, Knoxville, Tennessee, USA
  • P.K. Saha
    JAEA/J-PARC, Tokai-mura, Japan
  Funding: This work has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.
A realistic full duty factor laser stripping charge exchange injection scheme for future 1.3 GeV beam at the SNS is considered. Different schemes of laser stripping involving combinations of photoexcitation, photoionization and magnetic field stripping are calculated. The laser power and magnetic field strength needed for different approaches are estimated and compared. The most practical scheme of laser stripping is selected for development.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA33  
About • Received ※ 29 July 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 23 August 2022
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WEPA62 Design and Commissioning of the ASU CXLS RF System klystron, timing, electron, linac 764
  • B.J. Cook, G.I. Babic, J.R.S. Falconer, W.S. Graves, M.R. Holl, S.P. Jachim, R.E. Larsen
    Arizona State University, Tempe, USA
  Funding: This work was supported in part by NSF award #1935994.
The Compact X-ray Light Source (CXLS) uses inverse Compton scattering of a high intensity laser off a bright, relativistic electron beam to produce hard x-rays. The accelerator consists of a photoinjector and three standing-wave linac sections, which are powered by two 6-MW klystrons operating at 9.3 GHz with a repetition rate of 1 kHz. This paper presents the design and commissioning of the CXLS RF systems consisting of both high-power RF structures and low-power diagnostics. The high-power RF system is comprised of two solid state amplifier and klystron modulator sets, various directional couplers, and three phase shifter power dividers. The low-level system consists of a master oscillator and laser phase lock, IQ modulators, IQ demodulators, and downconverters. We present measurements of the low-level and high-power RF phase and amplitude stability showing RMS timing jitter in the tens of femtoseconds and amplitude jitter below 0.1% at high power.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA62  
About • Received ※ 29 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 19 August 2022
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THYD5 Development of Nanopatterned Strong Field Emission Cathodes cathode, electron, brightness, simulation 863
  • G.E. Lawler, N. Majernik, J.I. Mann, N. Montanez, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE HEP Grant DE-SC0009914.
Increasing brightness at the cathode is highly desirable for a diverse suite of applications in the electron accelerator community. These applications range from free electron lasers to ultrafast electron diffraction. Many options for higher brightness cathodes are under investigation notably semiconductor cathodes. We consider here the possibility for an alternative paradigm whereby the cathode surface is controlled to reduce the effective area of illumination and emission. We fabricated nanoblade metallic coated cathodes using common nanofabrication techniques. We have demonstrated that a beam can be successfully extracted with a low emittance and we have reconstructed a portion of the energy spectrum. As a result of our particular geometry, our beam possesses a notably high aspect ratio in its transverse plane. We can now begin to consider modifications for the production of intentionally patterned beams such as higher aspect ratios and hollow beams.
slides icon Slides THYD5 [4.652 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THYD5  
About • Received ※ 02 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 05 October 2022  
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THYD6 Arrival Time and Energy Jitter Effects on the Performance of X-Ray Free Electron Laser Oscillator FEL, cavity, electron, 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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THZE4 Experimental Characterization of Gas Sheet Transverse Profile Diagnostic diagnostics, electron, operation, MMI 907
  • N. Burger, G. Andonian, D.I. Gavryushkin, T.J. Hodgetts, A.-L.M.S. Lamure, M. Ruelas
    RadiaBeam, Santa Monica, California, USA
  • N.M. Cook, A. Diaw
    RadiaSoft LLC, Boulder, Colorado, USA
  • P.E. Denham, P. Musumeci, A. Ody
    UCLA, Los Angeles, USA
  • N.P. Norvell
    UCSC, Santa Cruz, California, USA
  • C.P. Welsch, M. Yadav
    The University of Liverpool, Liverpool, United Kingdom
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  Transverse profile diagnostics for high-intensity beams require solutions that are non-intercepting and single-shot. In this paper, we describe a gas-sheet ionization diagnostic that employs a precision-shaped, neutral gas jet. As the high-intensity beam passes through the gas sheet, neutral particles are ionized. The ionization products are transported and imaged on a detector. A neural-network based reconstruction algorithm, trained on simulation data, then outputs the initial transverse conditions of the beam prior to ionization. The diagnostic is also adaptable to image the photons from recombination. Preliminary tests at low energy are presented to characterize the working principle of the instrument, including comparisons to existing diagnostics. The results are parametrized as a function of beam charge, spot size, and bunch length.  
slides icon Slides THZE4 [2.051 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-THZE4  
About • Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 09 October 2022
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FRXD4 Suppressing the Microbunching Instability at ATF using Laser Assisted Bunch Compression electron, experiment, simulation, bunching 914
  • Q.R. Marksteiner, P.M. Anisimov, B.E. Carlsten, G. Latour, E.I. Simakov, H. Xu
    LANL, Los Alamos, New Mexico, USA
  Funding: This project was supported by funding from the Los Alamos National Laboratory Laboratory Research and Development program.
The microbunching instability in linear accelerators can significantly increase the energy spread of an electron beam. The instability can be suppressed by artificially increasing the random energy spread of an electron beam, but this leads to unacceptably high energy spreads for future XFEL systems. One possibility of suppressing this instability is to use laser assisted bunch compression (LABC) instead of the second chicane in an XFEL system, thereby eliminating the cascaded chicane effect that magnifies the microbunching instability. An experiment is proposed at ATF to test this concept, and numerical simulations of the experiment are shown.
slides icon Slides FRXD4 [4.629 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-FRXD4  
About • Received ※ 03 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 28 September 2022
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FRXD6 Bunch Length Measurements at the CEBAF Injector at 130 kV electron, simulation, cavity, gun 917
  • S. Pokharel, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • M.W. Bruker, J.M. Grames, A.S. Hofler, R. Kazimi, G.A. Krafft, S. Zhang
    JLab, Newport News, Virginia, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
In this work, we investigated the evolution in bunch length of beams through the CEBAF injector for low to high charge per bunch. Using the General Particle Tracer (GPT), we have simulated the beams through the beamline of the CEBAF injector and analyzed the beam to get the bunch lengths at the location of chopper. We performed these simulations with the existing injector using a 130 kV gun voltage. Finally, we describe measurements to validate these simulations. The measurements have been done using chopper scanning technique for two injector laser drive frequency modes: one with 500 MHz, and another with 250 MHz.
slides icon Slides FRXD6 [0.800 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-FRXD6  
About • Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 01 September 2022
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