Author: Muggli, P.
Paper Title Page
MOP088 A High Transformer Ratio Plasma Wakefield Accelerator Scheme for FACET 265
 
  • R.J. England, J.T. Frederico, M.J. Hogan
    SLAC, Menlo Park, California, USA
  • W. An, C. Joshi, W. Lu, W.B. Mori
    UCLA, Los Angeles, California, USA
  • P. Muggli
    USC, Los Angeles, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515
The ideal drive beam current profile for the plasma wakefield accelerator (PWFA) has been predicted by 1D and 2D simulations to be characterized by a triangular ramp that rises linearly from head to tail, followed by a sharp drop. A technique for generating such bunches experimentally was recently demonstrated. We present here an adaptation of this scheme to generate ramped bunches using the 23 GeV electron beam produced in the first two-thirds of the SLAC linac, and discuss plans to implement this scheme for high transformer ratio demonstration experiments at the FACET plasma wakefield accelerator facility.
 
 
MOP106 Electron Acceleration via Positron Driven Plasma Wakefield Accelerator 295
 
  • S.F. Pinkerton, P. Muggli
    USC, Los Angeles, California, USA
  • W. An, W.B. Mori
    UCLA, Los Angeles, California, USA
 
  Funding: Work supported by US DoE and NSF.
We show that a positron bunch with parameters accessible at FACET can excite a stable plasma wakefield over a few meters and a witness electron bunch experiences an accelerating gradient on the order of 10 GeV/m. Initial simulations show that the positron drive bunch is strongly affected by the transverse components of the wakefield: the positron bunch evolves significantly, which affects both the wakefield and witness bunch dynamics. Various solutions are presented, of which the positron-electron train shceme generates a desirable wakefield.
 
 
MOP158 Numerical Study of Plasma Wakefields Excited by a Train of Electron Bunches 391
 
  • Y. Fang, P. Muggli
    USC, Los Angeles, California, USA
  • C. Huang
    LANL, Los Alamos, New Mexico, USA
  • W.B. Mori
    UCLA, Los Angeles, California, USA
 
  Funding: Work supported by the US department of Energy
We study numerically the excitation of plasma wakefields by a train of electron bunches using the UCLA particle-in-cell code Quickpic*. We aim to find an optimal regime that combines both the advantages of linear and non-linear plasma wakefield accelerator. On one hand, the longitudinal electric field excited by individual bunches add as in the linear region, and the transformer ratio can be maximized (i.e. much larger than 2) by adjusting the number of particles in the bunches as well as their distance. On the other hand, the bunches create large wakefield independent of transverse sizes evolution while propagating through the plasma as in the non-linear region. In principle, such a scheme can multiply the energy of the witness bunch following the drive bunch train in a single plasma wakefield accelerating stage. The parameters for electron bunches are chosen based on the current experiment at the Brookhaven National Laboratory Accelerator Test Facility (ATF), where this scheme can be tested. Detailed simulation results will be presented.
* C. Huang, J. Comp. Phys.
 
 
MOP162 Betatron Radiation from an Off-axis Electron Beam in the Plasma Wakefield Accelerator 400
 
  • Y. Shi, O. Chang, P. Muggli
    USC, Los Angeles, California, USA
  • W. An, C. Huang, W.B. Mori
    UCLA, Los Angeles, California, USA
 
  Funding: supported by US DoE
In the non-linear or blow-out regime of a plasma wakefield, the electrons of the accelerated bunch oscillate in a pure ion column. It was demonstrated that a single bunch can emit betatron radiation in the keV to MeV range*. In a drive/witness bunch system, the witness bunch can be injected into the ion column with a transverse momentum or initial radial offset, so that the whole bunch oscillates about the column axis as one marcro-electron. This results in a larger emitted power and higher photon energy. The energy loss due to radiation can be compensated for by the energy gain from the wakefield so that the emission process can be sustained over long distance. Detailed results will be presented about the characteristics of the witness bunch oscillations and radiation through numerical simulations** and calculations.
* S.Q. Wang, et al., Phys. Rev.Let., 88(13), 135004,(2002), D. K. Johnson et al., Phys. Rev. Lett. 97(17), 175003, (2006)
** C.H. Huang, et al., J. Comp. Phys., 217(2), 658, (2006)
 
 
MOP220 The Feasibility of Near-Field ODR Beam-Size Monitoring at 23 GeV at FACET 513
 
  • A.H. Lumpkin
    Fermilab, Batavia, USA
  • M.J. Hogan
    SLAC, Menlo Park, California, USA
  • P. Muggli
    USC, Los Angeles, California, USA
  • C. Yao
    ANL, Argonne, USA
 
  Funding: Work partially supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Extension of near-field optical diffraction radiation (ODR) imaging to the 23 GeV beams at the proposed FACET facility at SLAC has been evaluated. The beam- size sensitivity at the 10- to 20- μm σ level based on a simple model will be reported. Polarization effects are also seen to be important and will be discussed. The comparisons to previous experimental results and the modeling results indicate sufficient feasibility for planning of the experiments in the coming year.
 
 
TUOBN3 Witness Bunch Acceleration in a Multi-bunch PWFA 712
 
  • P. Muggli, B.A. Allen, Y. Fang
    USC, Los Angeles, California, USA
  • M. Babzien, M.G. Fedurin, K. Kusche, R. Malone, C. Swinson, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by US DoE and NSF
We present initial experimental results showing the excitation of plasma wakefields by a train of two drive bunches. These wakefields are experienced by a trailing witness bunch that gains energy while retaining a finite energy spread. These well controlled plasma wakefield accelerator (PWFA) experiments are important to test the theory of the PWFA and serve as a testbed for techniques that will be used in high energy experiments.
 
slides icon Slides TUOBN3 [5.432 MB]  
 
WEP107 CSR Shielding Experiment 1677
 
  • V. Yakimenko, A.V. Fedotov, M.G. Fedurin, D. Kayran
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • P. Muggli
    USC, Los Angeles, California, USA
 
  It is well known that the emission of coherent synchrotron radiation (CSR) in a dipole magnets leads to increase in beam energy spread and emittance. At the Brookhaven National Laboratory Accelerator Test Facility (ATF) we study the suppression of CSR emission affect on electron beam in a dipole magnet by two vertically spaced conducting plates. The gap between the plates is controlled by four actuators and could be varied from 0 to 14 mm. Our experimental results show that closing the plates significantly reduces both the beam energy loss and CSR-induced beam energy spread. In this paper we present selected results of the experiment and compare then with rigorous analytical theory.  
 
WEP126 Progress in Experimental Study of Current Filamentation Instability 1719
 
  • B.A. Allen, P. Muggli
    USC, Los Angeles, California, USA
  • M. Babzien, M.G. Fedurin, K. Kusche, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • C. Huang
    LANL, Los Alamos, New Mexico, USA
  • J.L. Martins, L.O. Silva
    IPFN, Lisbon, Portugal
  • W.B. Mori
    UCLA, Los Angeles, California, USA
 
  Funding: Work supported by Department of Energy and National Science Foundation
Current Filamentation Instability, CFI, is of central importance for the propagation of relativistic electron beams in plasmas. CFI could play an important role in the generation of magnetic fields and radiation in the after-glow of gamma ray bursts and also in energy transport for the fast-igniter inertial confinement fusion concept. Simulations were conducted with the particle-in-cell code QuickPIC* for e- beam and plasma parameters at the Brookhaven National Laboratory – Accelerator Test Facility, BNL-ATF. Results show that for a 2cm plasma the instability reaches near saturation. An experimental program was proposed and accepted at the BNL-ATF and an experiment is currently underway. There are three components to the experimental program: 1) imaging of the beam density/filaments at the exit from the plasma, 2) measurement and imaging of the transverse plasma density gradient and measurement of the magnetic field and 3) identifying the radiation spectrum of the instability. Preliminary results from phase one will be presented along with the progress and diagnostic design for the following phases of the experiment.
* C. Huang et. al. Journal of Computational Physics 217, 2(2006)
 
 
TUOBN4 Plasma Wakefield Experiments at FACET 715
 
  • M.J. Hogan, R.J. England, J.T. Frederico, C. Hast, S.Z. Li, M.D. Litos, D.R. Walz
    SLAC, Menlo Park, California, USA
  • W. An, C.E. Clayton, C. Joshi, W. Lu, K.A. Marsh, W.B. Mori, S. Tochitsky
    UCLA, Los Angeles, California, USA
  • P. Muggli, S.F. Pinkerton, Y. Shi
    USC, Los Angeles, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration beginning in summer 2011. The nominal FACET parameters are 23GeV, 3nC electron bunches compressed to ~20μm long and focused to ~10μm wide. The intense fields of the FACET bunches will be used to field ionize neutral lithium or cesium vapor produced in a heat pipe oven. Previous experiments at SLAC demonstrated 50GeV/m gradients in an 85cm field ionized lithium plasma where the interaction distance was limited by head erosion. Simulations indicate the lower ionization potential of cesium will decrease the rate of head erosion and increase single stage performance. The initial experimental program will compare the performance of lithium and cesium plasma sources with single and double bunches. Later experiments will investigate improved performance with a pre-ionized cesium plasma. The status of the experiments and expected performance are reviewed.
 
slides icon Slides TUOBN4 [13.080 MB]  
 
TUOBN5 A Proposed Experimental Test of Proton-Driven Plasma Wakefield Acceleration Based on CERN SPS 718
 
  • G.X. Xia, A. Caldwell
    MPI-P, München, Germany
  • W. An, C. Joshi, W. Lu, W.B. Mori
    UCLA, Los Angeles, California, USA
  • R.W. Assmann, F. Zimmermann
    CERN, Geneva, Switzerland
  • R.A. Fonseca, N.C. Lopes, J. Vieira
    Instituto Superior Tecnico, Lisbon, Portugal
  • C. Huang
    LANL, Los Alamos, New Mexico, USA
  • K.V. Lotov
    BINP SB RAS, Novosibirsk, Russia
  • P. Muggli
    USC, Los Angeles, California, USA
  • A.M. Pukhov
    HHUD, Dusseldorf, Germany
  • L.O. Silva
    IPFN, Lisbon, Portugal
 
  Proton-driven plasma wakefield acceleration (PDPWA) has been proposed as an approach to accelerate electron beam to TeV energy regime in a single passage of plasma channel. An experimental test is recently proposed to demonstrate the capability of PDPWA by using proton beams from the CERN SPS. The preparation of experiment is introduced. The particle-in-cell simulation results based on realistic beam parameters are presented.  
slides icon Slides TUOBN5 [2.208 MB]