03 Particle Sources and Alternative Acceleration Techniques
A22 Plasma Wakefield Acceleration
Paper Title Page
TUPME049 Hosing Suppression in the Self-modulated Wakefield Accelerator 1473
 
  • J. Vieira
    IPFN, Lisbon, Portugal
  • W.B. Mori
    UCLA, Los Angeles, California, USA
  • P. Muggli
    MPI, Muenchen, Germany
 
  Funding: FCT-Portugal contract no EXPL/FIS-PLA/0834/1012; European Research Council contract no ERC-2010-AdG Grant 267841; by DOE contract no DE-SC0008491, DE-SC0008316, and DE-FG02- 92-ER40727.
The proton driven plasma wakefield accelerator (PDPWFA) uses short LHC proton (p+) bunches (shorter than the plasma wavelength) as drivers for strongly non-linear plasma waves. Simulations showed that the PDPWFA could be used to accelerate electrons to 600 GeVs in 600 m long plasmas*. Currently available p+ bunches are much longer than the plasma wavelength, being ideal to excite intese wakefields through the self-modulation instability (SMI). An experiment is being prepared at CERN to demonstrate SMI of p+ bunches. In addition, lepton SMI experiments are also being prepared at SLAC, DESY-PITZ and RAL. The hosing instability (HI) is a competing instability that may lead to beam breakup, and needs to be controlled over the long propagation distances required for SMI growth and saturation. In this work we show that the HI can be suppressed after SMI saturation in the linear wakefield excitation regime. SMI saturation before beam-break up can be achieved by seeding SMI, and as long as the initial bunch centroid displacements are within the initial bunch transverse size. The HI suppression occurs via a plasma analogue of the BNS damping in conventional accelerators.
* A. Caldwell et al, Nat. Physics Nat. Phys. 5, 363 (2009).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME049  
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TUPME050 Electron Bunch Self-modulation in Long Plasmas at SLAC FACET 1476
 
  • P. Muggli
    MPI, Muenchen, Germany
  • E. Adli, V.K.B. Olsen
    University of Oslo, Oslo, Norway
  • L.D. Amorim
    IST, Lisboa, Portugal
  • S.J. Gessner, M.J. Hogan, S.Z. Li, M.D. Litos
    SLAC, Menlo Park, California, USA
  • C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi
    UCLA, Los Angeles, California, USA
  • N.C. Lopes, J. Vieira
    Instituto Superior Tecnico, Lisbon, Portugal
  • O. Reimann
    MPI-P, München, Germany
 
  Funding: This work performed in part under DOE Contract DE-AC02-76SF00515.
We study the physics of self-modulation instability (SMI) of long, when compared to the wake wavelength, electron and positron bunches in pre-formed plasmas at SLAC-FACET. Self-modulation is the result of the action of focusing/defocusing transverse wakefields on the bunch radius. Self-modulation leads to observables such as overall defocusing of the bunch, periodic modulation of the bunch radius at the wake period and multi-GeV energy gain/loss by drive bunch particles. Defocusing is observed from OTR images, radial self-modulation from CTR spectra and interferometric traces and energy gain/loss from energy spectra with sub-GeV resolution. The plasma density is varied by changing the vapor density ionized by a laser/axicon system. The bunch length, radius and charge can also be varied. The SMI can be seeded using a notch collimator system. Numerical simulations indicate that seeding the SMI mitigates the hose instability. Hose instability can also be seeded, for example by using the RF deflecting cavity to impart a tilt to the incoming bunch axis. The overall experimental plan as well as the latest experimental results obtained with electron bunches will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME050  
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TUPME051 Self-Injection by Trapping of Plasma Electrons Oscillating in Rising Density Gradient at Vacuum-Plasma Interface 1479
 
  • A. A. Sahai, T.C. Katsouleas
    Duke ECE, Durham, North Carolina, USA
  • P. Muggli
    MPI-P, München, Germany
 
  Funding: DE-SC0010012, NSF-PHY-0936278
We model the trapping of plasma electrons within the density structures excited by a propagating energy source in a rising plasma density gradient. Rising density gradient leads to spatially contiguous coupled up-chirped plasmons (d{ω2pe(x)}/{dx}>0). Therefore phase mixing between plasmons can lead to trapping until the plasmon field is high enough such that e- trajectories returning towards a longer wavelength see a trapping potential. Rising plasma density gradients are ubiquitous for confining the plasma within sources at the vacuum-plasma interfaces. Therefore trapping of plasma-e- in a rising ramp is important for acceleration diagnostics and to understand the energy dissipation from the excited plasmon train [1]. Down-ramp in density [2][3] has been used for plasma-e- trapping within the first bucket behind the driver. Here, in rising density gradient the trapping does not occur in the first plasmon bucket but in subsequent plasmon buckets behind the driver. Trapping reduces the Hamiltonian of each bucket where e- are trapped, so it is a wakefield-decay probe. Preliminary computational results for beam and laser-driven wakefield are shown.
1.Sahai, A. A. et.al.,Proc of IPAC2013, MOPAC10, Oct2013
2.Suk, H. et.al.,Phys. Rev.Lett. 86 2001 10.1103/PhysRevLett.86.1011
3.Dawson, J, Phys Rev 113 1959 10.1103/PhysRev.113.383
 
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TUPME064 Laser-driven Acceleration with External Injection at SINBAD 1515
 
  • J. Grebenyuk, R.W. Aßmann, U. Dorda, B. Marchetti
    DESY, Hamburg, Germany
 
  One of the important milestones to make plasma acceleration a realistic technology for user-applications is demonstration of bunch acceleration inside a plasma wake with minimal degradation of its quality. This can be achieved by external injection of beams into a plasma accelerator. SINBAD is a proposed dedicated accelerator research and development facility at DESY where amongst other topics laser-driven wakefield acceleration with external injection of ultra-short bunches will be exploited. To minimise energy-spread growth the bunch should occupy a small fraction of the plasma wavelength. In addition it has to be longitudinally synchronised with the laser driver to high accuracy. To avoid emittance growth the beam Twiss parameters have to be matched to the intrinsic beta-function of the plasma. To facilitate matching and synchronisation, acceleration at low plasma densities can be advantageous. We present a preparatory feasibility study for future plasma experiments at SINBAD using simulations with the particle-in-cell code OSIRIS. Field-gradient scaling laws are presented together with parameter scans of externally injected bunch, such as its injection phase, charge and length.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME064  
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TUPME069 Proton Electron Accelerator at CERN 1519
 
  • R. Tarkeshian
    MPI, Muenchen, Germany
 
  AWAKE is a proton driven plasma-wakefield acceleration at CERN*, that uses long proton bunches ~ 400 ps from the SPS. In a dense plasma, a long proton bunch is subject toμbunching at plasma period due to the self-modulation instability, SMI**. The self-modulated proton bunch generates large amplitude charge separation through resonant wakefield excitation. Numerical simulations show that when seeded the SMI can grow and saturate over ~4 m in a plasma with density in the (1-10) *1014/cc range. Seeding also allows for deterministic injection of witness bunches in the focusing and accelerating phase of the wakefields. The SPS proton bunch carrying kJ of energy is a unique driver for generation of ~ GeV/m wakefields through 10’s of meters of plasma. The side-injected electrons ~15 MeV can reach GeV energies. The AWAKE experimental layout, the physics of self-modulation, simulation results, plasma source under study, diagnostics plan for bunch modulation measurement using transverse coherent transition radiation***, and phasing of the witness bunch respect to the wave and synchronisation with diagnostics will be presented.****
*A. Caldwel, et. al, Nature Physics 5, 2009
**N. Kumar, A. Pukhov, PRL, 104, 2010
***O. Reimann, R. Tarkeshian, Proc. of IBIC, 2013
**** The work is submitted on behalf of AWAKE collaboration.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME069  
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TUPME073 A Novel Laser Ionized Rb Plasma Source for Plasma Wakefield Accelerators 1522
 
  • E. Öz, F. Batsch, P. Muggli
    MPI-P, München, Germany
 
  Funding: AWAKE collaboration
A proton driven plasma wakefield accelerator* is to be conducted at CERN by the AWAKE collaboration. Externally injected electrons are accelerated in a large gradient (~GeV/m) wakefield. The large gradient is achieved by resonant formation of the wakefield by a train of micro-bunches. Transverse modulation of a long (~12 cm) proton bunch by the self modulation instability** creates these plasma wavelength size (~1 mm) micro-bunches. This resonant mechanism brings a strict requirement on the plasma density uniformity, namely % 0.2, in order for the injected electron bunch to remain in the accelerating and focusing phase of the wakefields. We describe the plasma source*** that satisfies this requirement during the beam plasma interaction. Rb vapor with ~1015 cm-3 density is confined in a 10 m long 4 cm diameter, stainless-steel tube which is heated to ~200 Co by an oil heat exchanger. The access to the source during interaction is provided by custom built fast valves. The vapor is fully tunnel ionized (first e-) by a laser forming a 2 mm diameter plasma channel.
* http://awake.web.cern.ch/awake/
** http://link.aps.org/doi/10.1103/PhysRevLett.104.255003
*** http://dx.doi.org/10.1016/j.nima.2013.10.093
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME073  
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TUPME074 First Experiences with the PITZ Plasma Cell for Electron Beam Self-modulation Studies 1525
 
  • M. Groß, A. Donat, J.D. Good, M. Khojoyan, G. Koss, M. Krasilnikov, R. Schütze, F. Stephan, G. Vashchenko
    DESY Zeuthen, Zeuthen, Germany
  • R. Brinkmann
    DESY, Hamburg, Germany
  • F.J. Grüner, G. Pathak
    Uni HH, Hamburg, Germany
  • P. Muggli, E. Öz
    MPI-P, München, Germany
  • D. Richter
    HZB, Berlin, Germany
  • C.B. Schroeder
    LBNL, Berkeley, California, USA
 
  The self-modulation of long particle beams in a plasma has recently gained interest in light of the ongoing preparation for the plasma wakefield acceleration experiment of the AWAKE collaboration at CERN. Instrumental to the experiment is the self-modulation of a proton beam to generate bunches short enough for producing high acceleration fields. As electron bunches are easier to handle and the underlying physics is identical, it is judicious to first gain insight into the experimental conditions of the self-modulation of long particle beams in plasma by using electron bunches before progressing to the experiment with proton bunches. The experimental demonstration of self-modulation of an electron bunch is in preparation at the Photo Injector Test facility at DESY, location Zeuthen (PITZ). In this contribution the fabrication and first experimental tests towards a Lithium plasma cell are highlighted. The distinctive feature of this plasma cell is the addition of side ports for insertion of the ionization laser beam and for diagnostics purposes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME074  
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TUPME075 Simulations on Laser Wakefield Generation in a Parabolic Magnetic-plasma Channel 1528
 
  • D.N. Gupta, M. Singh
    University of Delhi, Delhi, India
  • D. Jang, H. Suk
    APRI-GIST, Gwangju, Republic of Korea
  • B.S. Sharma
    Kota University, Rajasthan, India
 
  To utilize the laser-plasma channel for laser wakefield acceleration, we have studied the non-paraxial theory of nonlinear propagation of ultra-intense relativistic Gaussian laser pulse in a preformed spatially tapered magneto-plasma channel having a parabolic density profile. A three-dimensional envelope equation for the laser field is derived, which includes the non-paraxial and applied magnetic field effects. An analytical expression for the wakefield is derived and analyzed the results with the help of particle-in-cell (PIC) simulations. It is shown that wakefield structures and the phase of axial component of the wakefield depend on applied external magnetic field. This aspect of theoretical observation can be used in the production of highly collimated mono-energetic x-rays.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME075  
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TUPME076 Numerical modeling of the E-209 self-modulation experiment at SLAC - FACET 1531
 
  • L.D. Amorim, L.O. Silva, J. Vieira
    IPFN, Lisbon, Portugal
  • P. Muggli
    MPI, Muenchen, Germany
 
  The E-209 experiment currently running at SLAC- FACET used a long electron bunch (∼ 5 times the plasma wavelength) to drive plasma wakefields through the self- modulation instability. In this work we present and analyze numerical simulation results performed with the particle-in- cell (PIC) code OSIRIS. The results show that SMI saturates after 5cm of propagation in the plasma and that the maxi- mum acceleration wakefields, 15 − 20GV/m, are sustained over a 1m long plasma. Electron bunch energy loss of 4GeV was observed in the simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME076  
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TUPME077 The Challenge of Interfacing the Primary Beam Lines for the AWAKE Project at CERN 1534
 
  • C. Bracco, B. Goddard, E. Gschwendtner, M. Meddahi, A.V. Petrenko
    CERN, Geneva, Switzerland
  • P. Muggli
    MPI, Muenchen, Germany
  • F.M. Velotti
    EPFL, Lausanne, Switzerland
 
  The Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) at CERN foresees the simultaneous operation of a proton, a laser and an electron beam. The first stage of the experiment will consist in proving the self-modulation, in the plasma, of a long proton bunch into micro-bunches. The success of this experiment requires an almost perfect concentricity of the proton and laser beams, over the full length of the plasma cell. The complexity of integrating the laser into the proton beam line and fulfilling the strict requirements in terms of pointing precision of the proton beam at the plasma cell are described. The second stage of the experiment foresees also the injection of electron bunches to probe the accelerating wakefields driven by the proton beam. Studies were performed to evaluate the possibility of injecting the electron beam parallel and with an offset to the proton beam axis. This option would imply that protons and electrons will have to share the last few meters of a common beam line. Issues and possible solutions for this case are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME077  
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TUPME078 Electron Injection Studies for the AWAKE Experiment at CERN 1537
 
  • A.V. Petrenko, C. Bracco, E. Gschwendtner
    CERN, Geneva, Switzerland
  • K.V. Lotov
    NSU, Novosibirsk, Russia
  • K.V. Lotov
    BINP SB RAS, Novosibirsk, Russia
  • P. Muggli
    MPI, Muenchen, Germany
 
  The AWAKE experiment recently approved at CERN will use the self-modulation instability (SMI) of long (12 cm), relativistic (400 GeV/c) proton bunches in dense plasmas to drive wakefields with accelerating gradients at the GV/m level. These accelerating gradients will be probed by externally injected electrons. In order to preserve the plasma uniformity required for the SMI the first experiments will use on-axis injection of a low energy 10-20 MeV electron beam collinearly with the proton beam. In this article we describe the physics of electron injection into the proton driven SMI wakefields. Requirements on the injected electron beam are determined and the final accelerated beam parameters are obtained via numerical simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME078  
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TUPME079 A Spectrometer for Proton Driven Plasma Wakefield Accelerated Electrons at AWAKE 1540
 
  • S. Jolly, L.C. Deacon, J.A. Goodhand, S.R. Mandry, M. Wing
    UCL, London, United Kingdom
  • S.R. Mandry
    MPI, Muenchen, Germany
 
  The AWAKE experiment is to be constructed at the CERN Neutrinos to Gran Sasso facility (CNGS). This will be the first experiment to demonstrate electron acceleration by use of a proton driven plasma wakefield. The 400 GeV proton beam from the CERN SPS will excite a wakefield in a plasma cell several metres in length. To observe the plasma wakefield, electrons of a few MeV will be injected into the wakefield following the head of the proton beam. Simulations indicate that electrons will be accelerated to GeV energies by the plasma wakefield. The AWAKE spectrometer is intended to measure both the peak energy and energy spread of these accelerated electrons. The baseline design makes use of a single dipole magnet to separate the electrons from the proton beam. The dispersed electron beam then impacts on a scintillator screen: the resulting scintillation light is collected and recorded by an intensified CCD camera. The design of the spectrometer is detailed with a focus on the scintillator screen. Results of simulations to optimise the scintillator are presented, including studies of the standard GadOx scintillators commonly used for imaging electrons in plasma wakefield experiments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME079  
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TUPME081 Plasma Wakefield Acceleration at CLARA PARS 1544
SUSPSNE025   use link to see paper's listing under its alternate paper code  
 
  • K. Hanahoe, Ö. Mete, G.X. Xia
    UMAN, Manchester, United Kingdom
  • D. Angal-Kalinin, J.A. Clarke, J.K. Jones, J.W. McKenzie, B.L. Militsyn, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • D. Angal-Kalinin, J.A. Clarke, J.K. Jones, J.W. McKenzie, Y. Wei, C.P. Welsch, P.H. Williams
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • B. Hidding
    USTRAT/SUPA, Glasgow, United Kingdom
  • J.D.A. Smith
    TXUK, Warrington, United Kingdom
  • Y. Wei, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
 
  PARS is a proposed Plasma Accelerator Research Station using the planned CLARA (Compact Linear Accelerator for Research and Applications) electron linear accelerator at Daresbury Laboratory in the UK. In this paper, two- dimensional particle-in-cell simulations based on realistic CLARA beam parameters are presented. The results show that an accelerating gradient of 2.0 GV/m can be achieved over an accelerating length of at least 13 cm. Preliminary simulation results for a two bunch scheme show an energy gain of 70% over a length of 13 cm, giving an average accelerating gradient of 1.2 GeV/m.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME081  
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WEXB01 Breaking the 70 MeV Proton Energy Threshold in Laser Proton Acceleration and Guiding Beams to Applications 1886
 
  • M. Roth, S. Bedacht, S. Busold, O. Deppert, G. Schaumann, A. Tebartz, F. Wagner
    TU Darmstadt, Darmstadt, Germany
  • V. Bagnoud, A. Blazevic, D. Schumacher
    GSI, Darmstadt, Germany
  • C. Brabetz
    IAP, Frankfurt am Main, Germany
  • T.E. Cowan
    HZDR, Dresden, Germany
  • K. Falk, A. Favalli, J.C. Fernandez, C. Gautier, C.E. Hamilton, R.P. Johnson, K. Schoenberg, T. Shimada, G.A. Wurden
    LANL, Los Alamos, New Mexico, USA
  • M. Geißel, M. Schollmeier
    Sandia National Laboratories, Albuquerque, New Mexico, USA
  • D. Jung
    Queen's University of Belfast, Belfast, Northern Ireland, United Kingdom
  • F. Kroll
    Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
 
  This talk covers recent developments in laser plasma ion acceleration describing the technological challenges in breaking of energy threshold of 70 MeV. The presentation also highlights the recent experimental achievements towards laser ion acceleration and transport in the LIGHT collaboration.  
slides icon Slides WEXB01 [15.155 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEXB01  
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