MC5: Beam Dynamics and EM Fields
D09 Emittance Manipulation, Bunch Compression and Cooling
Paper Title Page
TUWPLS1
Beam Shaping Via 6D Phase-Space Manipulation  
 
  • Y. Sun
    ANL, Argonne, 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.
An electron beam obtained directly out of an injector does not always have the phase-space properties required for its optimum use. Phase-space manipulation is often necessary to achieve certain beam distributions in the transverse and longitudinal dimensions. There are many ways to accomplish the control of transverse beam profile such as using focusing magnets or shaping masks, and re-partition of the transverse phase-spaces. In comparison, less resources are available to arbitrarily shape the longitudinal distribution directly. However, owing to the transverse-to-longitudinal emittance exchange technique first demonstrated at the Fermilab A0 Photo-injector, the longitudinal beam profiles can be obtained by first shaping the beam transversely, followed by mapping the transverse distribution into longitudinal. Longitudinal beam profile manipulation via EEX has been greatly advanced at the Argonne Wakefield Accelerator and precise tailoring for various longitudinal beam profiles has been achieved. In this talk we will present the progress on beam shaping via 6D phase-space manipulation and discuss future research in the area.
 
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WEPTS016 Longitudinal Beam Manipulation by RF Phase Modulation at the Karlsruhe Research Accelerator 3123
 
  • A. Mochihashi, E. Blomley, T. Boltz, E. Huttel, B. Kehrer, A.-S. Müller, M. Schuh
    KIT, Karlsruhe, Germany
  • D. Teytelman
    Dimtel, San Jose, USA
 
  At the storage ring KARA (Karlsruhe Research Accelerator) of the Karlsruhe Institute of Technology (KIT) we have installed a function for the RF phase modulation to the low-level RF system. By choosing proper conditions of the modulation, the electron distribution on the longitudinal phase space can be changed in a large range. There are several applications of this longitudinal manipulation to the accelerator operation: an improvement of the beam lifetime and suppression of collective instabilities. We have performed tracking simulations for the longitudinal beam manipulation by the RF phase modulation. The results have implied that the longitudinal phase space distribution strongly depends on the modulation frequency. We have also performed experiments, which aimed at improving the beam lifetime in 2.5 GeV KARA multi-bunch operations. In this contribution, the low-level RF system at KARA, the simulation and experimental results under the RF phase modulation will be presented. As one of the options of the modulation, we consider manipulation of the internal fine structure in the longitudinal phase space by the modulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS016  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS034 Generation of Sub-Femtosecond Electron Beams and Electron Bunch Trains With High Form Factor Using Wake Field Structures 3174
 
  • Z. Dong, H. Chen, X.J. Deng, Y. C. Du, Z. Zhou
    TUB, Beijing, People’s Republic of China
 
  In this paper, we propose two beam manipulation methods with wakefield structures in a photo-injector. First, we propose a simple scheme to compensate non-linear effects during ballistic bunching by using a wakefield structure. Simulations have shown beams of 1 pC charge can be compressed to 1.56 fs rms, and even shorter beams (a few hundred attoseconds) can be obtained with bunch charge well below 1 pC. In the second part, a method of producing bunch trains with high form factor is proposed by using multiple wake-field structures. Simulation results have shown the production of a train with a form factor of 0.5 using a 1 nC beam at few-MeV energy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS034  
About • paper received ※ 11 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS055 Energy Modulation of Electron Beam in Corrugated Dielectric Waveguide 3248
 
  • A. Lyapin, S.T. Boogert, S.M. Gibson, K. Lekomtsev
    JAI, Egham, Surrey, United Kingdom
  • A. Aryshev, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  • A.A. Tishchenko
    MEPhI, Moscow, Russia
  • A.A. Tishchenko
    NRC, Moscow, Russia
 
  Energy modulated electron beams have a wide range of applications in accelerator physics, for example they can serve as drivers in resonant wakefield acceleration schemes. A strong wakefield induced energy modulation can be produced using a dielectric lined waveguide, the resultant micro-bunched beam is capable of producing coherent terahertz radiation *. We report on observation of energy modulation due to self-wakefields in a few picosecond duration and ~1 nC charge electron bunches of LUCX facility at KEK. To produce the modulation, we used a corrugated dielectric waveguide with an inner radius of 2 mm and a period of corrugation of 10 mm. In this case, the period of corrugation is longer than the wavelength of the main accelerating mode. We show electromagnetic simulations of on-axis electric fields leading to an optimisation of the corrugation period allowing to enhance the accelerating/decelerating fields compared to dielectric lined waveguides with a constant inner radius.
* S. Antipov et al., Experimental observation of energy modulation in electron beams passing though terahertz dielectric wakefield structures, PRL 108, 144801 (2012).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS055  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS066 Suppression of Correlated Energy Spread Using Emittance Exchange 3275
 
  • J. Seok, M. Chung
    UNIST, Ulsan, Republic of Korea
  • M.E. Conde, G. Ha, J.G. Power
    ANL, Argonne, Illinois, USA
 
  An emittance exchange (EEX) provides a precise longitudinal phase space manipulation of electron bunch. It has been studied for an easy and precise control of temporal distribution, but controls of energy distribution have not been explored. Since the energy control using EEX is under the identical principle to the temporal control, the EEX beamline can control a correlated energy spread of the electron bunch. This would benefit accelerator facilities requiring a low energy spread such as X-ray Free Electron Laser Oscil-lator (XFELO). In this paper, we present principle and preliminary simulation work on the suppression of correlated energy spread using the EEX beamline. ing the EEX beamline.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS066  
About • paper received ※ 21 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS093 Emittance Preservation for LCLS-II-HE Project 3333
 
  • J. Wu, T.O. Raubenheimer, M.D. Woodley
    SLAC, Menlo Park, California, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
A small transverse slice emittance at the undulator entrance is essential for high performance of the free electron laser. To achieve this, preservation of the phase space density of the electron bunch during acceleration and compression is absolutely necessary. The LCLS-II-HE is designed to transport a 100 pC bunch with an emittance of ~0.3 mm-mrad with minimal emittance dilution. However, in simulations starting from a normalized emittance on the order of 0.1 mm-mrad, the emittance growth is significant. In this paper, the sources of emittance growth are studied along the accelerator, in particular, around the laser-heater, the two bunch compressors. We have investigated mechanisms of emittance growth such as space charge, coherent synchrotron radiation, chromatic aberration, and spurious dispersion. Due to the extremely small emittance from the injector, 3-D space charge effect is important to determine the space charge dominated region and emittance dominated region. With this understanding, emittance preservation schemes are proposed. Studies are carried out with IMPACT simulation code, as well as ASTRA and ELEGANT.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS093  
About • paper received ※ 23 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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WEPTS094 Generation High-Charge of Flat Beams at the Argonne Wakefield Accelerator 3337
SUSPFO132   use link to see paper's listing under its alternate paper code  
 
  • T. Xu, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • M.E. Conde, G. Ha, J.G. Power, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • M. Kuriki
    HU/AdSM, Higashi-Hiroshima, Japan
  • P. Piot
    Fermilab, Batavia, Illinois, USA
 
  Funding: This work is supported by the U.S. DOE contracts No. DESC0017750, DE-SC0018656 with NIU, and No. DE-AC02-06CH11357 with ANL.
Beams with large transverse emittance ratios (flat beams)have received renewed interest for their possible applications in future linear colliders and advanced accelerators. A flat beam can be produced by generating a magnetized beam and then repartitioning its emittance using three skew quadrupoles. In this paper, we report on the experimental generation of∼1nC flat beams at the Argonne WakefieldAccelerator (AWA). The emittance ratio of the flat beam is demonstrated to be continuously variable by adjusting the magnetic field on the cathode.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS094  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS099 Passive Absorbers for Maximizing the Performance of the Mu2e-II Experiment 3345
 
  • J. Manczak
    IFIC, Valencia, Spain
  • J. Manczak
    Warsaw University, Warsaw, Poland
  • D.V. Neuffer, D. Stratakis
    Fermilab, Batavia, Illinois, USA
 
  The Fermilab’s Mu2e experiment is designed to search for Charged Lepton Flavour Violation in direct, neutrinoless conversion of muon into electron in the presence of a nucleus’ electromagnetic field. Quantity, which is going to be observed is the ratio between the rate of the above BSM (Beyond Standard Model) reaction and the rate of the standard muon capture on the nucleus. The measurement precision is expected to reach up to 10-17. Mu2e-II is the codename for the second phase of the experiment planned to run with the lower energy, higher intensity primary proton beam provided by PIP-II accelerator, currently under construction. The ionization cooling with a wedge absorber is introduced to Mu2e-II setup for potential increase in the number of low momentum muons reaching the target. The study is made into the position and size of the wedge inside the beamline using G4Beamline simulation framework. Results show an increase up to 12% for muons with momentum P below 30 MeV/c and 7% for muons with P<40 MeV/c when the beam is measured right after the wedge. Further studies are necessary to investigate how this gain can be delivered to the stopping target.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS099  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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