05: Beam Dynamics and EM Fields
Paper Title Page
TUZBB1
Physics of the MBA Lattice  
 
  • R.R. Lindberg
    ANL, Lemont, Illinois, USA
 
  Funding: Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
Multi-bend achromat (MBA) lattices were proposed more than 25 years ago as a way to reduce the emittance of third generation storage rings by 1-2 orders of magnitude, and thereby increase the x-ray brightness by a similar factor. However, it wasn’t until the recent advances in compact magnets and vacuum pumping, pioneered by MAX-IV and CERN, respectively, that MBA lattices could be considered as the basis for a light source. Now, there are many projects around the world that employ an MBA lattice to achieve an emittance well below 1 nm. I will begin by briefly reviewing how the MBA lattice can achieve an ultra-low emittance. Then, I will proceed to discuss how the essential physics of the MBA drives its design, and how that in turn impacts the physics. For example, its requirement for strong magnets leads to a small dynamic aperture and physically small vacuum chambers, which in turn impacts impedance and collective effects. I will try to illustrate this interplay with advances made by many other projects, but will inevitably favor the recent progress of the APS-Upgrade project, where we are targeting a 42-pm design for hard x-rays.
 
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TUZBB2 Reaching Low Emittance in Synchrotron Light Sources by Using Complex Bends 352
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  • G.M. Wang, J. Choi, O.V. Chubar, Y. Hidaka, T.V. Shaftan, S.K. Sharma, V.V. Smaluk, C.J. Spataro, T. Tanabe
    BNL, Upton, New York, USA
  • N.A. Mezentsev
    BINP SB RAS, Novosibirsk, Russia
 
  All modern projects of low-emittance synchrotrons follow Multi-Bend Achromat approach*. The low emittance is realized by arranging small horizontal beta-function and dispersion in the bending magnets, the number of which varies from 4 to 9 magnets per cell. We propose an alternative way to reach low emittance by use of a lattice element that we call "Complex Bend"**, instead of regular dipole magnets. The Complex Bend is a new concept of bending magnet consisting of a number of dipole poles interleaved with strong alternate focusing so as to maintain the beta-function and dispersion oscillating at very low values. The details of Complex Bend, considerations regarding the choice of optimal parameters, thoughts for its practical realization and use in low-emittance lattices, are discussed.
* MBA: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.495.2446&rep=rep1&type=pdf
** Complex Bend: Phys. Rev. Accel. Beams 21, 100703 (2018)
 
slides icon Slides TUZBB2 [7.894 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBB2  
About • paper received ※ 01 September 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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TUZBB3 Precise Beam Velocity Matching for the Experimental Demonstration of Ion Cooling With a Bunched Electron Beam 356
 
  • S. Seletskiy, M. Blaskiewicz, K.A. Drees, A.V. Fedotov, W. Fischer, D.M. Gassner, R.L. Hulsart, D. Kayran, J. Kewisch, K. Mernick, R.J. Michnoff, T.A. Miller, G. Robert-Demolaize, V. Schoefer, H. Song, P. Thieberger, P. Wanderer
    BNL, Upton, New York, USA
 
  The first ever electron cooling based on the RF acceleration of electron bunches was experimentally demonstrated on April 5, 2019 at the Low Energy RHIC Electron Cooler (LEReC) at BNL. The critical step in obtaining successful cooling of the Au ion bunches in the RHIC cooling sections was the accurate matching of average longitudinal velocities of electron and ion beams corresponding to a relative error of less than 5·10-4 in the e-beam momentum. Since the electron beam kinetic energy is just 1.6 MeV, measuring the absolute e-beam energy with sufficient accuracy and eventually achieving the electron-ion velocity matching was a nontrivial task. In this paper we describe our experience with measuring and setting the e-beam energy at LEReC.  
slides icon Slides TUZBB3 [1.340 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBB3  
About • paper received ※ 26 August 2019       paper accepted ※ 31 August 2019       issue date ※ 08 October 2019  
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TUZBB4 Space Charge Study of the Jefferson Lab Magnetized Electron Beam 360
SUPLM23   use link to see paper's listing under its alternate paper code  
 
  • S.A.K. Wijethunga, J.R. Delayen, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • J.F. Benesch, F.E. Hannon, C. Hernandez-Garcia, G.A. Krafft, M.A. Mamun, M. Poelker, R. Suleiman, S. Zhang
    JLab, Newport News, Virginia, USA
 
  Magnetized electron cooling could result in high luminosity at the proposed Jefferson Lab Electron-Ion Collider (JLEIC). In order to increase the cooling efficiency, a bunched electron beam with high bunch charge and high repetition rate is required. We generated magnetized electron beams with high bunch charge using a new compact DC high voltage photo-gun biased at -300 kV with alkali-antimonide photocathode and a commercial ultrafast laser. This contribution explores how magnetization affects space charge dominated beams as a function of magnetic field strength, gun high voltage, laser pulse width, and laser spot size.  
slides icon Slides TUZBB4 [12.582 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBB4  
About • paper received ※ 28 August 2019       paper accepted ※ 31 August 2019       issue date ※ 08 October 2019  
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TUZBB5 Transverse Ion Beam Emittance Growth Due to Low Frequency Instabilities in Microwave Ion Source Plasma 363
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  • C. Mallick, M. Bandyopadhyay, R. Kumar
    Institute for Plasma Research, Bhat, Gandhinagar, India
 
  The ion source is accompanied by the generation of low frequency (LF) plasma instabilities (PI). Its signature is also visible in high current heavy ion beam required for any accelerator. These LFs affect the profile of the ion beam in transverse phase-space. These issues are investigated in detail by measuring the emittance of beam. Beam oscillations are extracted from the transverse emittance data by taking Fast Fourier Transform (FFT) of it. PI frequencies are identified in the measured electromagnetic emission from the plasma, in which these frequencies appeared as sidebands around pump frequency 2.45 GHz. The PI components i.e.,ion acoustic (IA) and ion cyclotron (IC) waves are also visible in the FFT spectra. Low and high frequency oscillations in the beam are 476 kHz and ~1.3 MHz respectively. These two groups of frequencies also exist within the PI induced IA (238 - 873 kHz) and IC (1.29 - 1.3 MHz) frequency ranges. The measured emittance (rms-normalized) in horizontal and vertical phase-space varies from 0.002-0.098 𝜋 mm mrad and 0.004-0.23 𝜋 mm mrad respectively. PI induced beam oscillation is the reason behind such broad transverse emittance growth.
Reference
’S. Kumar et al.,Phys. Rev. Accel. Beams 21, 093402 (2018)’
’R. D’Arcy et al., Nucl. Instrum. Methods Phys. Res. A 815 7(2016)’
’L. Groening et al., Phys. Rev. Lett. 113, 264802 (2014)’
 
slides icon Slides TUZBB5 [5.298 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBB5  
About • paper received ※ 26 August 2019       paper accepted ※ 02 September 2019       issue date ※ 08 October 2019  
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TUZBB6 Nonlinear Tune-Shift Measurements in the Integrable Optics Test Accelerator 368
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TUPLM32   use link to see paper's listing under its alternate paper code  
 
  • S. Szustkowski, S. Chattopadhyay
    Northern Illinois University, DeKalb, Illinois, USA
  • S. Chattopadhyay, A.L. Romanov, A. Valishev
    Fermilab, Batavia, Illinois, USA
  • N. Kuklev
    University of Chicago, Chicago, Illinois, USA
 
  Funding: US Department of Energy, Office of High Energy Physics, General Accelerator Research and Development (GARD) Program
The first experimental run of Fermilab’s Integrable Optics Test Accelerator (IOTA) ring aimed at testing the concept of nonlinear integrable beam optics. In this report we present the preliminary results of the studies of a nonlinear focusing system with two invariants of motion realized with the special elliptic-potential magnet. The key measurement of this experiment was the horizontal and vertical betatron tune shift as a function of transverse amplitude. A vertical kicker strength was varied to change the betatron amplitude for several values of the nonlinear magnet strength. The turn-by-turn positions of the 100 MeV electron beam at twenty-one beam position monitors around the ring were captured and used for the analysis of phase-space trajectories.
 
slides icon Slides TUZBB6 [12.888 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUZBB6  
About • paper received ※ 28 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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TUPLM01 Experimental Studies of Resonance Structure Dynamics With Space Charge 372
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  • L. Dovlatyan, T.M. Antonsen, B.L. Beaudoin, S. Bernal, I. Haber, D.F. Sutter, G.D. Wyche
    UMD, College Park, Maryland, USA
 
  Funding: Funding for this project is provided by DOE-HEP award #DE-SC0010301
Space charge is one of the fundamental limitations for next generation high intensity circular accelerators. It can lead to halo growth as well as beam loss, and affect resonance structure in ways not completely understood. We employ the University of Maryland Electron Ring (UMER), a circular 10 keV storage machine, to experimentally study the structure of betatron resonances for beams of varying degrees of space charge intensity. Experimental techniques such as tune scans and frequency maps are employed. Results are also compared to computer simulations using the WARP code.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM01  
About • paper received ※ 26 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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TUPLM03 Adjoint Approach to Accelerator Lattice Design 376
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  • T.M. Antonsen, B.L. Beaudoin, L. Dovlatyan, I. Haber
    UMD, College Park, Maryland, USA
 
  Funding: Supported by USDoE DESC0010301
Accelerator lattices are designed using computer codes that solve the equations of motion for charged particles in both prescribed and self-consistent fields. These codes are run in a mode in which particles enter a lattice region, travel for a finite distance, and have their coordinates recorded to assess various figures of merit (FoMs). The lattice is then optimized by varying the positions and strengths of the focusing elements. This optimization is done in a high dimensional parameter space, requiring multiple simulations of the particle trajectories to determine the dependence of the confinement on the many parameters. Sophisticated algorithms for this optimization are being introduced. However, the process is still time consuming. We propose to alter the design process using "adjoint" techniques [*]. Incorporation of an "adjoint" calculation of the trajectories and self-fields can, in several runs, determine the gradient in parameter space of a given FoM with respect to all lattice parameters. It includes naturally self-fields and can be embedded in existing codes such as WARP or Vorpal. The theoretical basis for the method and several applications will be presented.
* T. Antonsen, D. Chernin, J. Petillo, Adjoint Approach to Beam Optics Sensitivity Based on Hamiltonian Particle Dynamics, 2018 arXiv:1807.07898, Physics of Plasmas 26, 013109 (2019).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM03  
About • paper received ※ 23 August 2019       paper accepted ※ 13 September 2019       issue date ※ 08 October 2019  
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TUPLM07 First Experimental Observations of the Plasma-Cascade Instability in the CeC PoP Accelerator 379
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  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • Y.C. Jing, V. Litvinenko, J. Ma, I. Pinayev, G. Wang, Y.H. Wu
    BNL, Upton, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • K. Shih
    SBU, Stony Brook, New York, USA
 
  Preservation of the beam quality is important for attaining the desirable properties of the beam. Collective effects can produce an instability severely degrading beam emittance, momentum spread and creating filamentation of the beam. Microbunching instability for beams traveling along a curved trajectory, and space charge driven parametric transverse instabilities are well-known and in-depth studied. However, none of the above include a microbunching longitudinal instability driven by modulations of the transverse beam size. This phenomenon was observed for the first time during the commissioning of the CeC PoP experiment. Based on the dynamics of this instability we named it a Plasma-Cascade Instability (PCI). PCI can strongly intensify longitudinal micro-bunching originating from the beam’s shot noise, and even saturate it. Resulting random density and energy microstructures in the beam can become a serious problem for generating high quality electron beams. On the other hand, such instability can drive novel high-power sources of broadband radiation. In this paper we present our experimental observations of the PCI and the supporting results of the numerical simulations.  
poster icon Poster TUPLM07 [17.319 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM07  
About • paper received ※ 27 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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TUPLM08 Experimental Studies of Single Invariant Quasi-Integrable Nonlinear Optics at IOTA 383
SUPLM19   use link to see paper's listing under its alternate paper code  
 
  • N. Kuklev, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • S. Nagaitsev, A.L. Romanov, A. Valishev
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by National Science Foundation award PHY-1549132, the Center for Bright Beams. Fermi Research Alliance operates Fermilab under Contract DE-AC02-07CH11359 with the US Dept. of Energy.
The Integrable Optics Test Accelerator is a research electron and proton storage ring recently commissioned at the Fermilab Accelerator Science and Technology facility. Its research program is focused on testing novel techniques for improving beam stability and quality, notably the concept of non-linear integrable optics. In this paper, we report on run 1 results of experimental studies of a quasi-integrable transverse focusing system with one invariant of motion, a Henon-Heiles type system implemented with octupole magnets. Good agreement with simulations is demonstrated on key parameters of achievable tune spread, dynamic aperture, and invariant conservation. We also outline current simulation and hardware improvement efforts for run 2, planned for fall of 2019.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM08  
About • paper received ※ 28 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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TUPLM09 A Fast Method to Evaluate Transverse Coupled-Bunch Stability at Non-Zero Chromaticity 387
 
  • R.R. Lindberg
    ANL, Lemont, Illinois, USA
 
  Funding: Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
We present a dispersion relation that gives the complex growth rate for coupled-bunch instabilities at arbitrary chromaticity in terms of its value at zero chromaticity. We compare predictions of the theory to elegant tracking simulations, and show that there are two distinct regimes to stability depending upon whether the zero chromaticity growth rate is smaller or larger than the chromatic tune shift over the bunch. We derive an approximate expression that is easily solved numerically, and furthermore indicate how the formalism can be extended to describe arbitrary longitudinal potentials.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM09  
About • paper received ※ 25 August 2019       paper accepted ※ 01 September 2019       issue date ※ 08 October 2019  
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TUPLM11 Beam-Beam Damping of the Ion Instability 391
 
  • M. Blaskiewicz
    BNL, Upton, New York, USA
 
  Funding: Work Supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Beam-Beam damping of the Ion Instability The electron storage ring of the proposed electron ion collider at BNL has bunch charges as large as 50 nC and bunch spacings as small as 10 ns. For molecules like CO a dangerous buildup of positive ions is possible and a significant fraction of these ions can survive allowable clearing gaps. The instability is thus multi-turn and the weak damping required to stop the ion instabilty with an ideal clearing gap is ineffective here. The beam-beam force is highly nonlinear and a potent source of tune spread. Simulations employing several macro-particles per electron bunch and several ion macroparticles are used to estimate maximum gas densities for some common molecules. A simplified model is introduced and compared with simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM11  
About • paper received ※ 26 August 2019       paper accepted ※ 02 September 2019       issue date ※ 08 October 2019  
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TUPLM12 Method for a Multiple Square Well Model to Study Transverse Mode Coupling Instability 395
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  • M.A. Balcewicz, Y. Hao
    FRIB, East Lansing, Michigan, USA
  • M. Blaskiewicz
    BNL, Upton, New York, USA
 
  In the high intensity limit it can become difficult to simulate intense beams sufficiently within a short time scale due to collective effects. Semi-Analytic methods such as the Square Well Model*/AirBag Square Well** (SWM/ABS) exist to estimate collective effects within a short time scale. SWM/ABS discretizes the longitudinal confining potential into a single square well enforcing linearity for the case of linear transverse optics. A method is proposed here to extend the Square Well Method multiple square wells. This method preserves linearity properties that make it easily solvable within a short time scale as well as including nonlinear effects from the longitudinal potential shape.
*M. Blaskiewicz PRSTAB 1, 044201. 1998
**A. Burov PRAB 22, 034202. 2019
 
poster icon Poster TUPLM12 [1.818 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM12  
About • paper received ※ 27 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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TUPLM13 Two-Energy Storage-Ring Electron Cooler for Relativistic Ion Beams 399
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  • B. Dhital, J.R. Delayen, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • J.R. Delayen, Y.S. Derbenev, D. Douglas, G.A. Krafft, F. Lin, V.S. Morozov, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  An electron beam based cooling system for the ion beam is one of the commonly used approaches. The proposed two’energy storage-ring electron cooler consists of damping and cooling sections at markedly different energies connected by an energy recovering superconducting RF structure. The parameters in the cooling and damping sections are adjusted for optimum cooling of a stored ion beam and for optimum damping of the electron beam respectively. This paper briefly describes a two cavities model along with a third cavity model to accelerate and decelerate the electron beam in two energy storage ring. Based on our assumed value of equilibrium emittance shows that these models give a bunch length of the order of cm and energy spread of the order of 〖10〗-5 in the cooling section which are required parameters for the better cooling. Numerical calculations along with elegant simulation are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM13  
About • paper received ※ 28 August 2019       paper accepted ※ 03 September 2019       issue date ※ 08 October 2019  
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TUPLM15 Arbitrary Transverse Profile Shaping using Transverse Wigglers 403
 
  • G. Ha, M.E. Conde, J.G. Power
    ANL, Lemont, Illinois, USA
 
  Funding: This work is supported by the U.S. Department of Energy, Offices of HEP and BES, under Contract No. DE-AC02-06CH11357.
Argonne Wakefield Accelerator (AWA) group demonstrated arbitrary longitudinal shaping capability of thee emittance exchange (EEX) beamline in 2016. Several different transverse masks were used to shape the beam transversely, and the transmission through the mask was around 40%. The masking is one of the easiest ways to control the profile, but this low transmission would make significant drop of the beam quality due to a higher charge requirement in the gun, and it can make thermal issues for high repetition rate or high intensity beams. At the same time, it only controls the profile not a 2D phase space. We recently proposed a scheme to generate a tunable bunch train using a EEX beamline with a transverse wiggler. This wiggler provides a sinusoidal magnetic field which makes a sinusoidal modulation on the transverse phase space. If the beam passes series of transverse wigglers with different period and strength, one can make arbitrary correlation on the horizontal position and momentum. It opens up totally new way to control all longitudinal properties including arbitrary current profile shaping without charge loss. In this poster, we present the concept of the work and plan.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM15  
About • paper received ※ 02 September 2019       paper accepted ※ 13 September 2019       issue date ※ 08 October 2019  
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TUPLM16 Double-Horn Suppression in EEX Based Bunch Compression 407
 
  • J. Seok, M. Chung
    UNIST, Ulsan, Republic of Korea
  • M.E. Conde, G. Ha, J.G. Power
    ANL, Lemont, Illinois, USA
 
  Nonlinearities on the longitudinal phase space in-duce a double-horn current profile when the bunch is compressed strongly. Since this double-horn can de-grade the performance of FELs due to the CSR it makes, the suppression of the double-horn is one of important beam dynamics issues. Emittance exchange (EEX) can be interesting option for this issue due to its longitudinal controllability. Since EEX exchanges the longitudinal phase space and transverse phase space, higher order magnets such as octupole can control the nonlinearity. In this paper, we present simulation re-sults on the suppression of the double-horn current profile using EEX based bunch compression. We use a double EEX beamline installed at the Argonne Wake-field Accelerator facility for the simulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM16  
About • paper received ※ 03 September 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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TUPLM18 Improving Energy Resolution and Compensating Chromatic Aberration With a TM010 Microwave Cavity 411
 
  • C.J.R. Duncan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • P. Cueva, J.M. Maxson, D.A. Muller
    Cornell University, Ithaca, New York, USA
 
  Funding: National Science Foundation under Award OIA-1549132, the Center for Bright Beams
The intrinsic energy spread of electron sources limits the achievable resolution of electron microscopes in both spectroscopic and spatially resolved measurements. We propose that the TM010 mode of a single radio frequency (RF) cavity be used to dramatically reduce this energy spread in a pulsed beam. We show with analytic approximations, confirmed in simulations, that the non-linear time-energy correlations that develop in an electron gun can be undone by the RF cavity running near-crest. We derive an expression that gives the required RF field strength as a function of accelerating voltage. We explore multiple applications, including EELS and SEM. By pulsing a photocathode with commercially available, high repetition-rate lasers, our scheme could yield competitive energy spread reduction at higher currents when compared with monochromated continuous-wave sources for electron microscopes.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM18  
About • paper received ※ 27 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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TUPLM20 Generation of High-Charge Magnetized Electron Beams Consistent With JLEIC Electron Cooling Requirements 414
SUPLM21   use link to see paper's listing under its alternate paper code  
 
  • A.T. Fetterman, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • S.V. Benson, F.E. Hannon, S. Wang
    JLab, Newport News, Virginia, USA
  • D.J. Crawford, D.R. Edstrom, P. Piot, J. Ruan
    Fermilab, Batavia, Illinois, 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 and DE-AC02-07CH11359.
The proposed Jefferson Lab Electron-Ion Collider (JLEIC), currently under design, relies on electron cooling in order to achieve the desired luminosity. This includes an electron beam with >55 Mev, 3.2 nC bunches that cools hadron beams with energies up to 100 GeV. To enhance the cooling, the electron beam must be magnetized with a specific eigen-emittance partition. This paper explores the use of the Fermilab Accelerator Science and Technology (FAST) facility to demonstrate the generation of an electron beam with parameters consistent with those required in the JLEIC high-energy cooler. We demonstrate via simulations the generation of the required electron-beam parameters and perform a preliminary experiment to validate FAST capabilities to produce such beams.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM20  
About • paper received ※ 07 September 2019       paper accepted ※ 19 November 2019       issue date ※ 08 October 2019  
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TUPLM21 Optical Stochastic Cooling Program at Fermilab’s Integrable Optics Test Accelerator 418
 
  • J.D. Jarvis, S. Chattopadhyay, V.A. Lebedev, H. Piekarz, P. Piot, A.L. Romanov, J. Ruan
    Fermilab, Batavia, Illinois, USA
  • S. Chattopadhyay, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: Fermi National Accelerator Laboratory is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Beam cooling enables an increase of peak and average luminosities and significantly expands the discovery potential of colliders. Optical Stochastic Cooling (OSC) is a high-bandwidth cooling technique that will advance the present state-of-the-art, stochastic-cooling rate by more than three orders of magnitude. A proof-of-principle demonstration with protons or heavy ions involves prohibitive costs, risks and technological challenges; however, exploration of OSC with electrons is a cost-effective alternative for studying the beam-cooling physics, optical systems and diagnostics. The ability to demonstrate OSC was a key requirement in the design of Fermilab’s Integrable Optics Test Accelerator (IOTA) ring. The IOTA program will explore the physics and technology of OSC in amplified and non-amplified configurations. We also plan to investigate the cooling and manipulation of a single electron stored in the ring. The OSC apparatus is currently being fabricated, and installation will begin in the fall of 2019. In this contribution, we will describe the IOTA OSC program, the upcoming passive-OSC experimental runs and ongoing preparations for an amplified-OSC experiment
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM21  
About • paper received ※ 27 August 2019       paper accepted ※ 06 September 2019       issue date ※ 08 October 2019  
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TUPLM22 Off Axis Dependence of Current Dependent Coherent Tune Shifts in the UMER Ring 422
 
  • D.F. Sutter, B.L. Beaudoin, L. Dovlatyan
    UMD, College Park, Maryland, USA
 
  Funding: Work supported by U. S. Department of Energy grant number DESC00010301
The University of Maryland Electron Ring (UMER) was built to explore space charge effects in the extreme - beyond the space charge limit of most existing storage rings. At the nominal operating kinetic energy of 10 keV, the beam is also non relativistic. We have experimentally verified that the current dependent coherent tune shift obeys the Laslett formula over a wide current range for a cylindrical geometry and non penetrating magnetic fields when the beam is on axis; i.e. the average closed orbit displacement around the ring is essentially zero.* In the current experiment this measurement is extended to the change in current dependent coherent tune shift as the average closed orbit is moved off axis. It can be displaced over approximately ±10 mm of the vacuum pipe diameter of 50 mm without loss of beam. Because the 36 bending magnets in UMER are very short, we treat each of them as a local kick and then increment each by a calculated small amount to achieve the desired, global closed orbit displacement. Experimental results are compared to predictions by Zotter and others.
* D. für Sutter, M.Cornacchia, et al, "Current dependent tune shifts in the University of Maryland electron ring", NAPAC 2013.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM22  
About • paper received ※ 29 August 2019       paper accepted ※ 04 September 2019       issue date ※ 08 October 2019  
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TUPLM24 Electron Heating by Ions in Cooling Rings 426
 
  • H. Zhao, M. Blaskiewicz
    BNL, Upton, New York, USA
 
  Hadron beam cooling at high energy is a critical technique for Electron-Ion Colliders (EIC). We consider using an electron storage ring for the EIC at BNL. For such a cooler, the electron beam quality plays an important role since it directly determines the cooling rate. Besides the effects of IBS, space charge and synchrotron damping, which are calculable with well known methods, the heating effect by ions also needs to be carefully considered in electron beam dynamics. In this paper, we present an analytical model to calculate the heating rate by ions and give some example calculations. In addition, this model was benchmarked by applying it on the IBS calculation.
* Work supported by States Department of Energy
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM24  
About • paper received ※ 26 August 2019       paper accepted ※ 02 September 2019       issue date ※ 08 October 2019  
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TUPLM25 Connecting Gas-Scattering Lifetime and Ion Instabilities 430
 
  • B. Podobedov, M. Blaskiewicz
    BNL, Upton, New York, USA
 
  Recently there is a renewed interest in fast ion instability (FII) which is of concern for future low-emittance electron storage rings, such as MBA light sources and colliders, i.e. eRHIC. While analytical theories and numerical codes exist to model the effect, due to various assumptions and limitations, accurate experimental verification is often desirable. Unfortunately, one of the most critical parameters for FII (as well as the classical "trapped-ion" instability), the residual ion concentration, is usually the most uncertain. Vacuum gauges and residual gas analyzers (RGAs) provide some useful data, but they are often not accurate enough, and, more importantly, they cannot directly probe the ion concentration along the beam orbit. In this paper we show how one could use gas-scattering lifetime measurements to infer the residual gas concentration suitable for ion instability experiment modelling.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM25  
About • paper received ※ 21 September 2019       paper accepted ※ 19 November 2019       issue date ※ 08 October 2019  
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TUPLM26 Progress Toward a Laser Amplifier for Optical Stochastic Cooling 434
SUPLM22   use link to see paper's listing under its alternate paper code  
 
  • A.J. Dick, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • M.B. Andorf
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Optical Stochastic Cooling (OSC) is a method of beam cooling using optical frequencies which compresses the phase space of the beam by correcting the deviation of each particle’s momentum. A particle bunch passing through an undulator produces radiation which is amplified and provides the corrective energy kick. In this project, we are testing a method of amplifying synchrotron radiation (SR) for the eventual use in OSC. The SR is amplified by passing through a highly-doped Chromium:Zinc Selenide (Cr:ZnSe) crystal which is pumped by a Thulium fiber laser. The SR will be produced by one of the bending magnets of the Advanced Photon Source. The first step is to detect and measure the power of SR using a photo-diode. The gain is then determined by measuring the radiation amplified after the single-pass through the crystal. This serves as a preliminary step to investigate the performance of the amplification of beam-induced radiation fields. The planned experiment is an important step towards achieving active OSC in a proof-of-principle demonstration in IOTA.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM26  
About • paper received ※ 02 September 2019       paper accepted ※ 13 September 2019       issue date ※ 08 October 2019  
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TUPLM33 Optimization of Beam Parameters for UEM with Photo-Emission S-Band RF Gun and Alpha Magnet 440
SUPLM24   use link to see paper's listing under its alternate paper code  
 
  • H.R. Lee, P. Buaphad, I.G. Jeong, Y. Joo, Y. Kim
    University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
  • P. Buaphad, I.G. Jeong, Y. Joo, Y. Kim
    KAERI, Jeongeup-si, Republic of Korea
  • B.L. Cho
    KRISS, Daejeon, Republic of Korea
  • M.Y. Han, J.Y. Lee, S.H. Lee
    Korea Atomic Energy Research Institute (KAERI), Daejeon, Republic of Korea
  • H. Suk
    GIST, Gwangju, Republic of Korea
 
  Ultrafast Electron Microscopy (UEM) is a powerful tool to observe ultrafast dynamical processes in sample materials at the atomic level. By collaborating with KRISS and GIST, the future accelerator R&D team at KAERI has been developing a UEM facility based on a photo-emission S-band (=2856 MHz) RF gun. Recently, we have added an alpha magnet in the beamline layout of the UEM to improve beam qualities such as emittance, divergence, energy spread, and bunch length. To achieve high spatial and time resolutions, we have been optimizing those beam parameters and other machine parameters by performing numerous ASTRA and ELEGANT code simulations. In this paper, we describe our ASTRA and ELEGANT code optimizations to obtain high-quality beam parameters for the UEM facility with a photo-emission S-band RF gun and an alpha magnet.  
poster icon Poster TUPLM33 [0.931 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM33  
About • paper received ※ 30 August 2019       paper accepted ※ 19 November 2019       issue date ※ 08 October 2019  
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TUPLM36 Temperature Measurements of the NSLS-II Vacuum Components 443
 
  • A. Blednykh, G. Bassi, C. Hetzel, B.N. Kosciuk, D. Padrazo Jr, T.V. Shaftan, V.V. Smaluk, G.M. Wang
    BNL, Upton, New York, USA
 
  This paper is dedicated to the analysis of our recent experience from ramp-up of operating current at NSLS-II from 25 mA at the end of commissioning in 2014 to 475 mA achieved in studies today. To approach the design level of the ring intensity we had to solve major problems in overheating of the chamber components. Since the beginning of the NSLS-II commissioning, the temperature of the vacuum components has been monitored by the Resistance Temperature Detectors located predominantly outside of the vacuum chamber and attached to the chamber body. A couple of vacuum components were designed with the possibility for internal temperature measurements under the vacuum as diagnostic assemblies. Temperature map helps us to control overheating of the vacuum components around the ring especially during the current ramp-up. The average current of 475mA has been achieved with two main 500MHz RF cavities and w/o any harmonic cavities. In this paper we discuss the heating results for a 15ps bunch length (at low current) of the following vacuum components: Large Aperture BPM, Small Aperture BPM, Bellows, Flanges, Ceramics Chambers and Stripline Kickers.  
poster icon Poster TUPLM36 [3.696 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM36  
About • paper received ※ 28 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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TUPLM37 High Energy Beam Transport Along the 68-m LANSCE 1L Beamline to Optimize Neutron Production 446
 
  • P.K. Roy, E.L. Kerstiens, R.J. Macek, C. Pillai, C.E. Taylor
    LANL, Los Alamos, New Mexico, USA
 
  Funding: *Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
An 800 MeV 100 µA proton beam is delivered to the Lujan Center, one of five user facilities at the LANSCE linear accelerator center, to generate an intense beam of pulsed neutrons. The Lujan Center beam transport line, known as 1L beamline, is over 68 meters in length, starting from the ROWS01. The beamline is consisted with bending and focusing elements before it reaches the end of the 1L beam optics system, where the beam spot size is nominally 1.5 cm (RMS). The Mark IV target assembly has been designed to optimize the neutron production for the 1L target in the Lujan center to improve the flux and resolution. As part of the safety review of this design, it becomes necessary to know the beam intensity and size on the new target. Using the new measurements of the beamline, calculated beam sizes using the LANL version of the beam envelope code TRANSPORT and CERN code MAD-X are compared. The input beam parameters for the codes were extracted from ORBIT analysis of the proton storage ring beam. Beam envelope measurements were made at various locations throughout the beamline using wire scanners. The predicted beam envelopes and measured data agree within expected errors.
*LA-UR-19-22889
 
poster icon Poster TUPLM37 [5.009 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM37  
About • paper received ※ 23 August 2019       paper accepted ※ 03 September 2019       issue date ※ 08 October 2019  
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WEXBA1
Beam Dynamics Measurements with New Generation BPMs  
 
  • B. Podobedov
    BNL, Upton, New York, USA
 
  Due to state-of-the-art NSLS-II beam position monitors, combined with advanced signal-processing techniques, we are now able to measure the difference between the betatron tunes of two (or more) bunches stored in the ring with the accuracy better than 10-6. For bunches of unequal charge this allows us to precisely determine the transverse kick factors. By applying local bumps, or, for in-vacuum undulators (IVUs), by varying the gap, we can also precisely measure the impedance of individual ring components. Since the tunes of unequally charged bunches are measured simultaneously, this reference method is virtually immune to machine drifts, as well as other systematic errors. For instance, in our IVU measurements vs. undulator gap, we can accurately determine current-dependent tuneshifts two orders of magnitude smaller than the tuneshift induced by the natural focusing of the undulator. Other examples of measurements performed with similar, or related, techniques include single-shot measurements of tune-shift with amplitude as well as non-invasive lattice characterization during user operations.  
slides icon Slides WEXBA1 [5.935 MB]  
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WEXBA2 Recent Results and Opportunities at the IOTA Facility 599
 
  • A.L. Romanov, D.R. Broemmelsiek, K. Carlson, D.J. Crawford, N. Eddy, D.R. Edstrom, J.D. Jarvis, V.A. Lebedev, S. Nagaitsev, J. Ruan, J.K. Santucci, V.D. Shiltsev, G. Stancari, A. Valishev, A. Warner
    Fermilab, Batavia, Illinois, USA
  • S. Chattopadhyay, S. Szustkowski
    Northern Illinois University, DeKalb, Illinois, USA
  • Y.K. Kim, N. Kuklev, I. Lobach
    University of Chicago, Chicago, Illinois, USA
 
  The Integrable Optics Test Accelerator (IOTA) was recently commissioned as part of the Fermilab Accelerator Science and Technology (FAST) facility. The IOTA ring was briefly operated with electrons at 47 MeV followed by a 6-months run with 100 MeV electrons. The main goal of the first run was to study beam dynamics in the integrable lattices with elliptical nonlinear magnets and in the quasi-integrable case with profiled octupole channel. The flexibility of the IOTA ring allowed a wide range of complementary studies, such as experiments with a single electron; studies of fluctuations in undulator radiation and operation with low emittance beams. Over the next year the proton injector will be installed and two runs carried out. One run will be dedicated to the refinement of nonlinear experiments and another will be dedicated to the proof-of-principle demonstration of Optical Stochastic Cooling.  
slides icon Slides WEXBA2 [12.702 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEXBA2  
About • paper received ※ 31 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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WEXBA3 CSR Phase Space Dilution in CBETA 605
SUPLM17   use link to see paper's listing under its alternate paper code  
 
  • W. Lou, G.H. Hoffstaetter, D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • C.E. Mayes
    SLAC, Menlo Park, California, USA
 
  CBETA, the Cornell BNL ERL Test Accelerator, will be the first multi-turn Energy Recovery Linac (ERL) with SRF accelerating cavities and Fixed Field Alternating gradient (FFA) beamline. While CBETA gives promise to deliver unprecedentedly high beam current with simultaneously small emittance, Coherent Synchrotron Radiation (CSR) can pose detrimental effect on the beam at high bunch charges and short bunch lengths. To investigate the CSR effects on CBETA, we used the established simulation code Bmad to track a bunch with different parameters. We found that CSR causes phase space dilution, and the effect becomes more significant as the bunch charge and recirculation pass increase. Potential ways to mitigate the effect involving varying phase advances are being investigated.  
slides icon Slides WEXBA3 [6.121 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEXBA3  
About • paper received ※ 28 August 2019       paper accepted ※ 15 September 2019       issue date ※ 08 October 2019  
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WEXBA4
Comparison of Numerical Methods for the Calculation of Synchrotron Radiation From Electrons  
 
  • F.Y. Li, B.E. Carlsten, R. Garimella, C.-K. Huang, T.J. Kwan
    LANL, Los Alamos, New Mexico, USA
 
  The phenomenon of synchrotron radiation from electrons is at the core of modern accelerator based light sources. While synchrotron radiation in the far field has been well established, the self-consistent beam dynamics due to the near-field synchrotron radiation becomes increasingly important as high-brightness beams and coherent light sources are developed. Since it is difficult to diagnose the near fields in experiments, accurate and efficient numerical methods are essential to the design of these light sources. Here, we investigate several existing methods for the calculation of the radiation near fields, including the finite difference method, the Lienard-Wiechert method and a novel near-field method. We compare the accuracy and efficiency of these methods in both 1D and multi-dimensions, for both steady-state and dynamic beam trajectories, both radiation field and space charge field, as well as for both coherent and incoherent fields. We also discuss a self-similarity feature in the synchrotron radiation that can be exploited to improve the calculation.
Work supported by the LDRD program at LANL.
 
slides icon Slides WEXBA4 [8.569 MB]  
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WEPLM13 Multipactor Electron Cloud Analysis in a 17 GHz Standing Wave Accelerator Cavity 687
SUPLM06   use link to see paper's listing under its alternate paper code  
 
  • H. Xu, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
 
  Funding: US Department of Energy High Energy Physics
Theoretical predictions of single-surface one-point multipactor modes have been confirmed in experiments with a 17 GHz standing wave single cell disk-loaded waveguide accelerator structure operated in gradient range of 45-90 MV/m. A dc-biased probe placed outside of a slit in the side wall of the structure was used to measure the internal dark current electron energy distribution. The results indicated that the electrons had kinetic energy up to about 50 eV, in agreement with our CST particle-in-cell (PIC) simulations. Further theoretical calculations were performed to calculate the frequency detuning introduced by the multipactor electron cloud on the cell side wall for different electron cloud thicknesses and densities. We found that the detuning (Δf/f) due to the electron cloud was small, about two orders of magnitude smaller than the reciprocal of the cavity loaded quality factor. This detuning is sufficiently small that it does not cause significant power reflection. Similar calculations were carried out for high gradient operation of accelerator structures at frequencies of 2.856 GHz and 110.0 GHz, showing similar small detuning by multipactor discharges.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM13  
About • paper received ※ 19 August 2019       paper accepted ※ 16 November 2020       issue date ※ 08 October 2019  
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WEPLS02 Simulation of a Klystron Input Cavity using a Steady-State Full-Wave Solver 768
SUPLM12   use link to see paper's listing under its alternate paper code  
 
  • A.R. Gold, S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  The simulation of vacuum electronic radio-frequency (RF) power sources is generally done through semi-analytical modeling approaches. These techniques are computationally efficient as they make assumptions on the source topology, such as the requirement that the electron beam travel longitudinally and interact with cylindrical modes. To simulate more general interactions, transient particle-in-cell (PIC) codes are currently required. We present here simulation results of a 5045 klystron using a newly developed steady state code which does not make assumptions on the beam configuration or geometry of the structure and resonant modes. As we solve directly for the steady-state system dynamics, this approach is computationally efficient yet, as demonstrated through comparison with experimental results, provides similar accuracy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS02  
About • paper received ※ 28 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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WEPLS03 Analytical Expression for a N-Turn Trajectory in the Presence of Quadrupole Magnetic Errors 772
SUPLM20   use link to see paper's listing under its alternate paper code  
 
  • Y. Rodriguez Garcia, J.F. Cardona
    UNAL, Bogota D.C, Colombia
  • Y. Rodriguez Garcia
    UAN, Bogotá D.C., Colombia
 
  The action and phase jump method is a technique, based on the use of turn-by-turn experimental data in a circular accelerator, to find and measure local sources of magnetic errors through abrupt changes in the values of action and phase. At this moment, this method uses at least one pair of adjacent BPMs (Beam Position Monitors) to estimate the action and phase at one particular position in the accelerator. In this work, we propose a theoretical expression to describe the trajectory of a charged particle for an arbitrary number of turns when a magnetic error is present in the accelerator. This expression might help to estimate action and phase at one particular position of the accelerator using only one BPM in contrast to the current method that needs at least two BPMs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS03  
About • paper received ※ 26 August 2019       paper accepted ※ 03 September 2019       issue date ※ 08 October 2019  
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WEPLS04 Simulations of Low Energy Au78+ Losses in RHIC 775
 
  • G. Robert-Demolaize, K.A. Drees, Y. Luo
    BNL, Upton, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The RHIC Run19 BES-II program features the commissioning of the Low Energy RHIC electron Cooling (LEReC) Project, which uses electron cooling techniques to compensate for intra-beam scattering and thus to improve the luminosity lifetime. During RHIC operations at 3.85 GeV (beam energy) with LEReC, one needs to ensure that the electron beam energy is properly matched for cooling purposes: if so, some of the circulating Au-79 ions can recombine with an electron, turning into Au-78 and circulating with a large momentum offset. Part of the LEReC commissioning steps is therefore to drive a maximized number of Au-78 ions towards a chosen location of the RHIC mechanical aperture to generate particle showers that can be detected by a Recombination Monitor outside the cryostat. This article introduces the baseline lattice design, then discusses the few scenarios considered for optimizing Au-78 losses at a given location. Each scenario is then simulated using new tracking tools for generating beam loss maps.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS04  
About • paper received ※ 27 August 2019       paper accepted ※ 03 September 2019       issue date ※ 08 October 2019  
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WEPLS05 Simulation Analysis of the LCLS-II Injector using ACE3P and IMPACT 779
 
  • D.A. Bizzozero, J. Qiang
    LBNL, Berkeley, California, USA
  • L. Ge, Z. Li, C.-K. Ng, L. Xiao
    SLAC, Menlo Park, California, USA
 
  Funding: This work is supported by the Director of the Office of Science of the US Department of Energy under contracts DEAC02-05CH11231 and DE-AC02-76-SF00515.
The LCLS-II beam injector system consists of a 186 MHz normal-conducting RF gun, a two-cell 1.3 GHz normal-conducting buncher cavity, two transverse focusing solenoids, and eight 1.3 GHz 9-cell Tesla-like super-conducting booster cavities. With a coordinated effort between LBNL and SLAC, we have developed a simulation workflow combining the electromagnetic field solvers from ACE3P with the beam dynamics modeling code IMPACT. This workflow will be used to improve performance and minimize beam emittance for given accelerator structures through iterative optimization. In our current study, we use this workflow to compare beam quality parameters between using 2D axisymmetric field profiles and fully 3D non-axisymmetric fields caused by geometrical asymmetries (e.g. RF coupler ports).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS05  
About • paper received ※ 20 August 2019       paper accepted ※ 04 September 2019       issue date ※ 08 October 2019  
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WEPLS09 Fast Two-Dimensional Calculation of Coherent Synchrotron Radiation in Relativistic Beams 783
SUPLM08   use link to see paper's listing under its alternate paper code  
 
  • J. Tang, G. Stupakov
    SLAC, Menlo Park, California, USA
 
  Coherent Synchrotron Radiation(CSR) in a relavistic beam during compression can lead to longitudinal modulation of the bunch with wavelength smaller than bunch length and is regarded as one of the main sources of emittance growth in the bunch compressor. Current simulations containing CSR wake fields often utilize one-dimensional model assuming a line beam. Despite its good computation efficiency, 1D CSR model can be inaccurate in many cases because it ignores the so-called ’compression effect’. On the other hand, the existing 3D codes are often slow and have high demands on computational resources. In this paper we propose a new method for calculation of the three-dimensional CSR wakefields in relativistic beams with integrals of retarded potentials. It generalizes the 1D model and includes the transient effects at the entrance and the exit from the magnet. Within given magnetic lattice and initial beam distributions, the formalism reduces to 2D or 3D integration along the trajectory and therefore allows fast numerical calculations using 2D or 3D matrices.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS09  
About • paper received ※ 28 August 2019       paper accepted ※ 04 September 2019       issue date ※ 08 October 2019  
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WEPLS10 Modeling of Space-Charge Effects in the ORISS MRTOF Device for Applications to FRIB 786
SUPLM16   use link to see paper's listing under its alternate paper code  
 
  • R. Hipple
    MSU, East Lansing, Michigan, USA
  • S.M. Lund
    FRIB, East Lansing, Michigan, USA
 
  The Oak Ridge Isotope/Isomer Spectrometer and Separator (ORISS) is an electrostatic multiply reflecting time-of-flight (MRTOF) mass separator constructed by the University Radioactive Ion Beam Consortium (UNIRIB) and Louisiana State University. The device was never fully commissioned, and was eventually shipped to Michigan State University for use at the Facility for Rare Isotopes and Beams (FRIB). The separation process is sensitive to space-charge effects due to the reflection of ions at both ends of the trap, as well as nonlinearities in the optics. In this study we apply the time-based particle-in-cell code Warp to model the effects of intense space-charge during the separation process. We find that the optics can be tuned for isochronous operation and focusing in the presence of intense space-charge to enable separation of bunches with high particle counts. This suggests the device may be effectively utilized at FRIB as a separator, spectrograph and spectrometer.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS10  
About • paper received ※ 28 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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WEPLS11 Simulation of Transparent Spin Experiment in RHIC 789
 
  • H. Huang, Y.S. Derbenev, F. Lin, V.S. Morozov, Y. Zhang
    JLab, Newport News, Virgina, USA
  • P. Adams, H. Huang, F. Méot, V. Ptitsyn, W.B. Schmidke
    BNL, Upton, New York, USA
  • Y. Filatov
    MIPT, Dolgoprudniy, Moscow Region, Russia
  • A.M. Kondratenko, M.A. Kondratenko
    Science and Technique Laboratory Zaryad, Novosibirsk, Russia
 
  Funding: Work supported by the U.S. DOE under Contracts No. DE-AC05-06OR23177 and DE-AC02-98CH10886.
The transparent spin mode has been proposed as a new technique for preservation and control of the spin polari-zation of ion beams in a synchrotron. The ion rings of the proposed Jefferson Lab Electron-Ion Collider (JLEIC) adopted this technique in their figure-8 design. The transparent spin mode can also be setup in a racetrack with two identical Siberian snakes. There is a proposal to test the predicted features of the spin transparent mode in Relativistic Heavy Ion Collider (RHIC), which already has all of the necessary hardware capabilities. We have earlier analytically estimated the setup parameters and developed a preliminary experimental plan. In this paper we describe simulation setup and benchmarking for the proposed experiment using a Zgoubi model of RHIC.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS11  
About • paper received ※ 03 September 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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WEPLS12 A Semi-Analytical Approach to Six-Dimensional Path-Dependent Transport Matrices With Application to High-Brightness Charged-Particle Beam Transport 792
 
  • C.-Y. Tsai
    HUST, Wuhan, People’s Republic of China
  • K. Fan
    Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
 
  Funding: This work was supported by the Fundamental Research Funds for the Central Universities under Project No. 5003131049.
Efficient and accurate estimate of high-brightness electron beam dynamics is an important step to the overall performance evaluation in modern particle accelerators. Utilizing the moment description to study multi-particle beam dynamics, it is necessary to develop a path-dependent transport matrix, together with application of the drift-kick algorithm*. In this paper we will construct semi-analytical models for three typical beam transport elements, solenoid with fringe fields, transverse deflecting cavity, and a beam slit. To construct the semi-analytical models for these elements, we begin by formulating the simplified single-particle equations of motion, and apply typical numerical techniques to solve the corresponding six-by-six transport matrix as a function of the path coordinate. The developed semi-analytical models are demonstrated with three practical examples, where our numerical results are discussed, compared with and validated by particle tracking simulations. These path-dependent transport matrix models can be incorporated to the analysis based on beam matrix method for the application to high-brightness charged-particle beam transport.
* C.-Y. Tsai et al., Nuclear Inst. And Methods in Physics Research, A 937 (2019) 1-20
 
poster icon Poster WEPLS12 [3.099 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS12  
About • paper received ※ 20 August 2019       paper accepted ※ 03 September 2019       issue date ※ 08 October 2019  
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WEPLS14 A C++ TPSA/DA Library With Python Wrapper 796
 
  • H. Zhang, Y. 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.
Truncated power series algebra (TPSA) or differential algebra (DA) is often used by accelerator physicists to generate a transfer map of a dynamic system. The map then can be used in dynamic analysis of the system or in particle tracking study. TPSA/DA can also be used in some fast algorithms, eg. the fast multipole method, for collective effect simulation. This paper reports a new TPSA/DA library written in C++. This library is developed based on Dr. Lingyun Yang’s TPSA code, which has been used in MAD-X and PTC. Compared with the original code, the updated version has the following changes: (1) The memory management has been revised to improve the efficiency; (2) A new data type of DA vector is defined and supported by most frequently used operators; (3) Support of inverse trigonometric functions and hyperbolic functions for the DA vector has been added; (4) function composition is revised for better efficiency; (5) a python wrapper is provided. The code is hosted at github and available to the public.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLS14  
About • paper received ※ 20 September 2019       paper accepted ※ 16 November 2020       issue date ※ 08 October 2019  
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WEPLE02 Integrated Accelerator Simulation with Electromagnetics and Beam Physics Codes 885
 
  • L. Ge, Z. Li, C.-K. Ng, L. Xiao
    SLAC, Menlo Park, California, USA
  • D.A. Bizzozero, J. Qiang, J.-L. Vay
    LBNL, Berkeley, California, USA
  • D.P. Grote
    LLNL, Livermore, California, USA
 
  Funding: Work supported by US Department of Energy under contracts AC02-76SF00515, DE-AC02-05CH11231 and DE-AC52-07NA27344. Used resources of the National Energy Research Scientific Computing Center.
This paper presents an integrated simulation capability for accelerators including electromagnetic field and beam dynamics effects. The integrated codes include the parallel finite-element code suite ACE3P for electromagnetic field calculation of beamline components, the parallel particle-in-cell (PIC) code IMPACT for beamline particle tracking with space-charge effects, and the parallel self-consistent PIC code Warp for beam and plasma simulations. The common data format OpenPMD has been adopted for efficient field and particle I/O data transfer between codes. One application is to employ ACE3P and IMPACT for studying beam qualities in accelerator beamlines. Another is to combine ACE3P and Warp for investigating plasma processing for operational performance of RF cavities. A module for mapping the CAD geometry used in ACE3P to Warp Cartesian grid representation has been developed. Furthermore, a workflow has been implemented that enables the execution of integrated simulation on HPC systems. Examples for simulation of the LCLS-II injector using ACE3P-IMPACT and plasma ignition in SRF cavities using ACE3P-Warp will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE02  
About • paper received ※ 20 August 2019       paper accepted ※ 19 November 2019       issue date ※ 08 October 2019  
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WEPLE04 Recent Developments and Applications of Parallel Multi-Physics Accelerator Modeling Suite ACE3P 888
 
  • Z. Li, L. Ge, C.-K. Ng, L. Xiao
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported by DOE Contract No. DE-AC02-76SF00515.
SLAC’s ACE3P code suite is developed to harness the power of massively parallel computers to tackle large complex problems with increased memory and solve them at greater speed. ACE3P parallel multi-physics codes are based on higher-order finite elements for superior geometry fidelity and better solution accuracy. ACE3P consists of an integrated set of electromagnetic, thermal and mechanical solvers for accelerator modeling and virtual prototyping. The use of ACE3P has contributed to the design and optimization of existing and future accelerator projects around the world. Multi-physics analysis on high performance computing (HPC) platform enables thermal-mechanical simulations of largescale systems such as the LCLS-II cryomodule. Recently, new capabilities have been added to ACE3P including a nonlinear eigenvalue solver for calculating mode damping, a moving window for pulse propagation in the time domain to reduce computational cost, thin layer coating representation using a surface impedance model, and improved boundary conditions using perfectly matched layers (PML) to terminate wave propagation. These new developments are presented in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE04  
About • paper received ※ 27 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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WEPLE05 Tracking With Space Harmonics in ELEGANT Code 892
 
  • Y.P. Sun, C. Yao
    ANL, Lemont, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The elegant code has the capability of simulating particle motion in accelerating or deflecting RF cavities, with a simplified (or ideal) model of the electromagnetic fields. To improve the accuracy of RF cavity simulations, the ability to track with space harmonics has been added to the elegant code. The sum of all the space harmonics will mimic the real electromagnetic fields in the RF cavity. These space harmonics will be derived from electromagnetic fields simulation of the RF cavity. This method should be general, which can be applied to any RF cavity structure, including accelerating and deflecting cavities.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE05  
About • paper received ※ 31 August 2019       paper accepted ※ 04 September 2019       issue date ※ 08 October 2019  
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WEPLE08 Parallel Tracking-Based Modeling of Gas Scattering and Loss Distributions in Electron Storage Rings 901
 
  • M. Borland
    ANL, Lemont, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Estimation of gas scattering lifetimes in storage rings is typically done using a simple approach that can readily be performed by hand. A more sophisticated approach uses linear mapping of the angular dynamic acceptance around the ring and allows including variation of gas pressure and composition*. However, neither approach is appropriate for highly nonlinear lattices, in which the angular acceptance does not map according to the linear optics. Further, these approaches provide no detailed information about the location of losses. To address these limitations, a tracking-based approach was implemented in the program Pelegant**. We describe the implementation and performance of this method, as well as several applications to the Advanced Photon Source Upgrade.
* M. Borland, J. Carter, H. Cease, and B. Stillwell, Proc. IPAC 2015, 546.
** Y. Wang and M. Borland, AIP Conf. Proc. 877, 241 (2006).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE08  
About • paper received ※ 27 August 2019       paper accepted ※ 04 September 2019       issue date ※ 08 October 2019  
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WEPLE09 Mitigation of Nonlinear Phase Space in a Space-Charge-Limited Injector Diode 905
 
  • W.D. Stem, Y.-J. Chen, J. Ellsworth
    LLNL, Livermore, USA
 
  Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
The performance of an accelerator is limited by the quality of the beam produced at the injector. For a Pierce-type diode structure, the cathode-shroud interface and the anode pipe entrance are sources for undesired, irreversible phase space nonlinearities that lead to emittance growth. In this contribution, we present ways to mitigate these nonlinearities by adjusting the cathode-shroud interface to meet the beam edge boundary conditions and by adjusting the solenoidal focusing magnet in the diode region such that the nonlinear focusing magnetic fringe fields compensate the nonlinear defocusing electrical fields of the anode pipe entrance.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE09  
About • paper received ※ 05 September 2019       paper accepted ※ 04 December 2019       issue date ※ 08 October 2019  
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WEPLE10 Simulating Space Charge Dominated Beam Dynamics Using FMM 909
 
  • S.A. Schmid, H. De Gersem, E. Gjonaj
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Dohlus
    DESY, Hamburg, Germany
 
  Funding: This work is supported by the DFG in the framework of GRK 2128.
In this contribution, we simulate the beam generation in the high brilliance photoinjector of the European XFEL developed at DESY-PITZ. The investigation addresses the influence of space charge on the emittance of bunches with up to 1.0 nC bunch charge. For the simulations, we implemented a mesh-less fast multipole method (FMM) in the 3D tracking code REPTIL. We present numerical convergence and performance studies as well as a validation with commonly used simulation tools ASTRA and KRACK3. Furthermore, we provide a machine parameter study to minimize the beam emittance in the injector.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLE10  
About • paper received ※ 27 August 2019       paper accepted ※ 04 September 2019       issue date ※ 08 October 2019  
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FRXBA1
Review of Recent Advances in Cooling Techniques  
 
  • S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
 
  Beam cooling plays an important role in future electron-ion colliders. The talk will review recent advances in cooling techniques. It will especially discuss variants of electron cooling such as e.g., coherent and micro-bunched electron cooling. Other cooling technique, e.g. optical stochastic cooling will also be presented.  
slides icon Slides FRXBA1 [8.091 MB]  
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FRXBA2
Diverse Beam Profile Shapings Through Nonlinear Focusing of Multipole Magnets in a Beam Transport Line  
 
  • Y. Yuri, T. Yuyama
    QST/Takasaki, Takasaki, Japan
  • M. Fukuda
    RCNP, Osaka, Japan
 
  It is well-known that the transverse intensity distribution of a charged-particle beam can be made approximately uniform through the nonlinear focusing force using multipole (mainly, octupole) magnets in a beam transport line. This fact indicates that the proper use of multipole magnets enables the diverse beam profile shapings that cannot be achieved by common linear focusing, such as quadrupole magnets. We have, therefore, investigated the feasibility of the beam profile shaping (other than uniform profiles) by means of nonlinear focusing. Recently, we have experimentally demonstrated the formation of an ion beam with a hollow transverse distribution using octupole and sextupole magnets. It has been found that the hollow beam has a steep peak at the radial edge and that its cross-sectional shape varies diversely depending on the order and strength of the applied multipole magnets. In the presentation, the first experimental result of the hollow-beam formation will be reported together with the theoretical analysis of the behavior of a nonlinear-focused beam. Moreover, other unique beam profiles obtained through the nonlinear force of the multipole magnets will also be shown.  
slides icon Slides FRXBA2 [4.111 MB]  
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FRXBA3 Applications and Opportunities for the Emittance Exchange Beamline 981
 
  • G. Ha, M.E. Conde, J.G. Power
    ANL, Lemont, Illinois, USA
  • M. Chung, J. Seok
    UNIST, Ulsan, Republic of Korea
 
  Funding: This work is supported by the U.S. Department of Energy, Offices of HEP and BES, under Contract No. DE-AC02-06CH11357.
Emittance exchange (EEX) provides a powerful method of controlling the longitudinal phase space using the relatively simpler methods of transverse control. An EEX beamline was installed at the Argonne Wakefield Accelerator (AWA) facility in 2015. Several experiments important to the wakefield acceleration, such as a high transformer ratio from shaped bunches, have already been demonstrated. We are currently developing several applications of the EEX beamline including temporal profile shaping, THz radiation generation, time-energy correlation control, diagnostic uses of EEX etc. We will present the on-going EEX program for longitudinal phase space control taking place at the AWA facility, and discuss recently discovered new opportunities.
 
slides icon Slides FRXBA3 [6.814 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-FRXBA3  
About • paper received ※ 02 September 2019       paper accepted ※ 02 September 2019       issue date ※ 08 October 2019  
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FRXBA4 Maximizing 2-D Beam Brightness Using the Round to Flat Beam Transformation in the Ultralow Charge Regime 986
SUPLM02   use link to see paper's listing under its alternate paper code  
 
  • F.W. Cropp V, P.E. Denham, J. Giner Navarro, E.T. Liu, P. Musumeci
    UCLA, Los Angeles, USA
  • N. Burger, L. Phillips
    PBPL, Los Angeles, USA
  • A.L. Edelen, C. Emma
    SLAC, Menlo Park, California, USA
 
  Funding: This work is supported by the United States National Science Foundation award PHY-1549132 (the Center for Bright Beams)
We seek to maximize the 2-D beam brightness in an RF photoinjector operating in an ultralow charge (<1 pC) regime by implementing the FBT. Particle tracking simulations suggest that in one dimension, normalized projected emittances smaller than 5 nm can be obtained at the UCLA Pegasus facility with up to 100 fC beam charge. A tunable magnetic field is put on the cathode. Three skew quadrupoles are used to block-diagonalize the beam matrix and recover the vastly different eigenemittances as the projected emittances. Emittance measurement routines, including grid-based, pepperpot-based and quad scan routines, have been developed for on-line calculation of the 4-D beam matrix and its eigenemittances. Preliminary measurements are in agreement with simulations and indicate emittance ratios larger than 10 depending on the laser spot size on the cathode. Fine tuning the quadrupole gradients for the FBT has a significant effect on the 2-D beam brightness. We have made concrete steps toward computer minimization and machine learning optimization of the quadrupole gradients in order to remove the canonical angular momentum from the beam and achieve the target normalized projected emittances.
 
slides icon Slides FRXBA4 [3.059 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-FRXBA4  
About • paper received ※ 28 August 2019       paper accepted ※ 05 December 2019       issue date ※ 08 October 2019  
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FRXBA5 The Role of Laser Shaping in Microbunching Instability Suppression and Seeded X-Ray Free Electron Emission 990
SUPLM09   use link to see paper's listing under its alternate paper code  
 
  • J. Tang, S. Carbajo, F.-J. Decker, Z. Huang, J. Krzywiński, R.A. Lemons, W. Liu, A.A. Lutman, G. Marcus, T.J. Maxwell, S.P. Moeller, D.F. Ratner, S. Vetter
    SLAC, Menlo Park, California, USA
 
  Microbunching instability (MBI) driven by collective effects in an accelerator is known to be detrimental for the performance of X-ray free electron lasers. At the Linac Coherent Light Source (LCLS), laser heater (LH) system was installed to suppress the microbunching instability by inducing a small amount of slice energy spread to the electron beam. The distribution of the induced energy spread greatly effects MBI suppression and can be controlled by shaping the transverse profile of the heater laser. In this paper, we present theoretical and experimental results on utilizing a Laguerre-Gaussian 01 Mode (LG01) laser at LCLS to obtain better suppression of the instability. We demonstrate experimentally that Gaussian-shaped energy distribution is induced by LG01 mode LH and final microbunching gain is better suppressed. We finally discuss the role of LH spatial shaping in soft X-ray self-seeded (SXRSS) FEL emission and demonstrate that this LH configuration is capable of generating high spectral brightness FEL pulses.  
slides icon Slides FRXBA5 [3.162 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-FRXBA5  
About • paper received ※ 28 August 2019       paper accepted ※ 12 September 2019       issue date ※ 08 October 2019  
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