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Muggli, P.

Paper Title Page
THPMS015 Observation of Multi-GeV Breakdown Thresholds in Dielectric Wakefield Structures 3026
 
  • M. C. Thompson, M. C. Thompson
    LLNL, Livermore, California
  • H. Badakov, J. B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  • M. J. Hogan, R. Ischebeck, N. A. Kirby, R. Siemann, D. R. Walz
    SLAC, Menlo Park, California
  • P. Muggli
    USC, Los Angeles, California
  • A. Scott
    UCSB, Santa Barbara, California
  • R. B. Yoder
    Manhattan College, Riverdale, New York
 
  Funding: This work was performed under the auspices of the US Department of Energy under Contracts No. DE-FG03-92ER40693, DE-AC02-76SF00515, W-7405-ENG-48, and DE-FG02-92-ER40745.

The breakdown threshold of a dielectric subjected to the GV/m-scale electric-fields of an intense electron-beam has been measured. In this experiment at the Final Focus Test Beam (FFTB) facility, the 30 GeV SLAC electron beam was focused down and propagated through short fused-silica capillary-tubes with internal diameters of as little as 100 microns. The electric field at the inner surface of the tubes was varied from about 1 GV/m to 22 GV/m by adjusting the longitudinal compression of the electron bunch. The onset of breakdown, as indicated by a bright discharge, was found to correlate to a surface field of about 4 GV/m. An analysis of the damage sustained to the beam-exposed fibers, and its correlation to field amplitude, is also reported.

 
THPMS030 Mitigation of Ion Motion in Future Plasma Wakefield Accelerators 3067
 
  • R. Gholizadeh, T. C. Katsouleas, P. Muggli
    USC, Los Angeles, California
  • W. B. Mori
    UCLA, Los Angeles, California
 
  Funding: DoE contract # DE-FG02-92-ER40745

Simulation and analysis of the ion motion and multiple ionization in a plasma wakefield accelerator is presented for the parameters required of a future ILC afterburner. We show that although ion motion leads to substantial emittance growth for extreme parameters of future colliders in the sub-micron spot size regime, several factors that can mitigate the effect are explored. These include sunchrotron damping, plasma density gradient and hot plasma.

 
THPMS031 Plasma Wakefield Acceleration Utilizing Multiple Electron Bunches 3070
 
  • E. Kallos, T. C. Katsouleas, P. Muggli
    USC, Los Angeles, California
  • W. D. Kimura
    STI, Washington
  • I. Pavlishin, I. Pogorelsky, D. Stolyarov, V. Yakimenko
    BNL, Upton, Long Island, New York
 
  Funding: DoE contract # DE-FG02-92-ER40745

We investigate various plasma wakefield accelerator schemes that rely on multiple electron bunches to drive a large amplitude plasma wave, which are followed by a witness bunch at a phase where it will sample the high acceleration gradient and gain energy. Experimental verifications of various two bunch schemes are available in the literature; here we provide analytical calculations and numerical simulations of the wakefield dependency and the transformer ratio when M drive bunches and one witness bunch are fed into a high density plasma, where M is between 2 and 10. This is a favorable setup since the bunches can be adjusted such that the transformer ratio and the efficiency of the accelerator are enhanced compared to single bunch schemes. The possibility of a five bunch ILC afterburner to accelerate a witness bunch from 100 GeV to 500 GeV is also examined.

 
THPMS032 Plasma Wakefield Acceleration Experiments using Two Subpicosecond Electron Bunches 3073
 
  • P. Muggli, E. Kallos, T. C. Katsouleas
    USC, Los Angeles, California
  • W. D. Kimura
    STI, Washington
  • K. Kusche, I. Pavlishin, D. Stolyarov, V. Yakimenko
    BNL, Upton, Long Island, New York
 
  Funding: This work is supported by US DoE under contracts DE-FG02-92-ER40745 and DE-FG02-04ER41294.

Two ~100 fs electron bunches, separated in energy by approximately 1.8 MeV and in time by 0.5-1 ps, were sent through a capillary discharge plasma. The plasma density was varied from ~1·1014/cc to ~1·1017/cc. A 2-D PWFA model indicates the net wakefield produced by the bunches will depend on their relative charge, temporal separation, and the plasma density. This will affect the amount of energy gain or loss of the second bunch. During measurements of the energy spectrum of the second bunch, we observed a difference in the amount of gain or loss depending on the plasma density, which is consistent with the model prediction.

 
THPMS033 Scaling of Energy Gain with Plasma Parameters in a Plasma Wakefield Accelerator 3076
 
  • P. Muggli, T. C. Katsouleas, E. Oz
    USC, Los Angeles, California
  • I. Blumenfeld, F.-J. Decker, M. J. Hogan, R. Ischebeck, R. H. Iverson, N. A. Kirby, R. Siemann, D. R. Walz
    SLAC, Menlo Park, California
  • C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
    UCLA, Los Angeles, California
 
  Funding: This work was supported by the Department of Energy contracts DE-AC02-76SF00515, DE-FG02-92ER40727, DE-FG02-92-ER40745. DE-FG02-03ER54721, DE-FC02-01ER41179 and NSF grant Phy-0321345.

Systematic measurements of energy gain as a function of plasma parameters in the SLAC electron beam-driven plasma wakefield acceleration (PWFA) experiments lead to very important understanding of the beam-plasma interaction. In particular, measurements as a function of the plasma length Lp show that the energy gain increases linearly with Lp in the 10 to 30 cm range. Based on this scaling, the plasma was subsequently lengthened to Lp=90cm, resulting in the first demonstration of the doubling of the energy of a fraction of the incoming 42GeV electrons*. The peak accelerating gradient is larger than 40GV/m and is sustained over meter-scale plasma lengths. These measurements also reveal that the optimum plasma density for acceleration is about 2.7·1017/cc, larger than the value predicted by the linear theory for the approximately 20 microns bunch length, confirming that the experiment is conducted in the non-linear regime of the PWFA. Detailed experimental results will be presented.

* "Energy doubling of 42 GeV electrons in a meter scale plasma wakefield accelerator", I. Blumenfeld et. al., Nature, 2006, accepted

 
THPMS034 Generation and Characterization of the Microbunched Beams with a Wire Mesh Target 3079
 
  • P. Muggli, E. Kallos
    USC, Los Angeles, California
  • M. Babzien, K. Kusche, V. Yakimenko
    BNL, Upton, Long Island, New York
  • W. D. Kimura
    STI, Washington
 
  Funding: Work supported by US Department of Energy contract DE-AC02-98CH10886

The presentation will cover experimental results on generation and measurement of the beams with theμbunches length from 1 to 50 microns at Brookhaven Accelerator Test Facility. Arbitrary number of microbunches is sliced out of 5 ps long beam using wire mesh and slits. The details of beam structure are characterized using CSR interferometer and 6 mm long plasma wakefield channel with the controllable plasma density.

 
THPMS037 ON THE POSSIBILITY OF ACCELERATING POSITRON ON AN ELECTRON WAKE AT SABER 3082
 
  • X. Wang, T. C. Katsouleas, P. Muggli
    USC, Los Angeles, California
  • R. Ischebeck
    SLAC, Menlo Park, California
  • C. Joshi
    UCLA, Los Angeles, California
 
  Funding: This work was supported by the Department of Energy contract DE-FG02-92-ER40745

A new approach for positron acceleration in non-linear plasma wakefields driven by electron beams is presented. Positrons can be produced by colliding an electron beam with a thin foil target embedded in the plasma. Integration of positron production and acceleration in one stage is realized by a single relativistic, intense electron beam. Simulations with the parameters of the proposed SABER facility at SLAC suggest that this concept could be tested there.

 
WEYKI01 Results of the Energy Doubler Experiment at SLAC 1910
 
  • M. J. Hogan, I. Blumenfeld, F.-J. Decker, R. Ischebeck, R. H. Iverson, N. A. Kirby, R. Siemann, D. R. Walz
    SLAC, Menlo Park, California
  • C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
    UCLA, Los Angeles, California
  • T. C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
 
  Funding: This work was supported by the Department of Energy contracts DE-AC02-76SF00515, DE-FG02-92ER40727, DE-FG02-92-ER40745. DE-FG02-03ER54721, DE-FC02-01ER41179 and NSF grant Phy-0321345.

The costs and the time scales of colliders intended to reach the energy frontier are such that it is important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators a drive beam, either laser or particle, produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultra-high accelerating fields over a substantial length to achieve a significant energy gain. More than 42 GeV energy gain was achieved in an 85 cm long plasma wakefield accelerator driven by a 42 GeV electron drive beam at the Stanford Linear Accelerator Center (SLAC). Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of ~52 GV/m. This effectively doubles their energy, producing the energy gain of the 3 km long SLAC accelerator in less than a metre for a small fraction of the electrons in the injected bunch.

 
slides icon Slides  
THPMS027 Dielectric Wakefield Accelerator Experiments at the SABER Facility 3058
 
  • G. Travish, H. Badakov, A. M. Cook, J. B. Rosenzweig, R. Tikhoplav
    UCLA, Los Angeles, California
  • M. K. Berry, I. Blumenfeld, F.-J. Decker, M. J. Hogan, R. Ischebeck, R. H. Iverson, N. A. Kirby, R. Siemann, D. R. Walz
    SLAC, Menlo Park, California
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • P. Muggli
    USC, Los Angeles, California
  • M. C. Thompson
    LLNL, Livermore, California
 
  Funding: Work supported in part by Department of Energy contracts DE-AC02-76SF00515, DE-FG02-92-ER40745, DE-FG03-92ER40693 and W-7405-ENG-48

Electron bunches with the unparalleled combination of high charge, low emittances, and short time duration, as first produced at the SLAC FFTB, are foreseen to be produced soon at the SABER facility. These types of bunches have enabled wakefield driven accelerating schemes of >10 GV/m. In the context of the Dielectric Wakefield Accelerators (DWA) such beams, having rms bunch length as short as 20 um, have been used to drive 100 μm and 200 μm ID hollow tubes above 20 GV/m surface fields. These FFTB tests enabled the measurement of a breakdown threshold in excess of 4 GV/m (2 GV/m accelerating field) in fused silica. With the construction and commissioning of the SABER facility at SLAC, new experiments are made possible to test further aspects of DWAs including materials, tube geometrical variations, direct measurements of the Cerenkov fields, and proof of acceleration in tubes >10 cm in length. The E169 collaboration will investigate breakdown thresholds and accelerating fields in new materials including CVD diamond. Here we describe the experimental plans, beam parameters, simulations, and progress to date as well as future prospects for machines based of DWA structures.

 
THPMS029 Beam Head Erosion in Self-ionized Plasma Wakefield Accelerators 3064
 
  • M. Zhou, C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori
    UCLA, Los Angeles, California
  • M. K. Berry, I. Blumenfeld, F.-J. Decker, M. J. Hogan, R. Ischebeck, R. H. Iverson, N. A. Kirby, R. Siemann, D. R. Walz
    SLAC, Menlo Park, California
  • T. C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
 
  Funding: Work supported by Department of Energy contracts DE-AC02-76SF00515, DE-FG02-92ER40727, DE-FG02-92-ER40745 DE-FG02-03ER54721, DE-FC02-01ER41179 and NSF grant Phy-0321345

In the recent plasma wakefield accelerator experiments at SLAC, the energy of the particles in the tail of the 42 GeV electron beam were doubled in less than one meter [1]. Simulations suggest that the acceleration length was limited by a new phenomenon – beam head erosion in self-ionized plasmas. In vacuum, a particle beam expands transversely in a distance given by beta*. In the blowout regime of a plasma wakefield [2], the majority of the beam is focused by the ion channel, while the beam head slowly spreads since it takes a finite time for the ion channel to form. It is observed that in self-ionized plasmas, the head spreading is exacerbated compared to that in pre-ionized plasmas, causing the ionization front to move backward (erode). A simple theoretical model is used to estimate the upper limit of the erosion rate for a bi-gaussian beam by assuming free expansion of the beam head before the ionization front. Comparison with simulations suggests that half this maximum value can serve as an estimate for the erosion rate. Critical parameters to the erosion rate are discussed.

[1] I. Blumenfeld et al., Nature 445, 741(2007)[2] J. B. Rosenzweig et al., Phys. Rev. A 44, R6189 (1991)

 
THPMS040 Correlation of Beam Parameters to Decelerating Gradient in the E-167 Plasma Wakefield Acceleration Experiment 3091
 
  • I. Blumenfeld, M. K. Berry, F.-J. Decker, M. J. Hogan, R. Ischebeck, R. H. Iverson, N. A. Kirby, R. Siemann, D. R. Walz
    SLAC, Menlo Park, California
  • C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
    UCLA, Los Angeles, California
  • T. C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
 
  Funding: This work was supported by the Department of Energy contracts DE-AC02-76SF00515, DE-FG02-92ER40727, DE-FG02-92-ER40745 DE-FG02-03ER54721, DE-FC02-01ER41179 and NSF grant Phy-0321345

Recent experiments at SLAC have shown that high gradient acceleration of electrons is achievable in meter scale plasmas. Results from these experiments show that the wakefield is sensitive to parameters in the electron beam which drives it. In the experiment the bunch length and beam waist location were varied systematically at constant charge. Here we investigate the correlation of peak beam current to the decelerating gradient. Limits on the transformer ratio will also be discussed. The results are compared to simulation.

 
FRPMS063 Material Effects and Detector Response Corrections for Bunch Length Measurements 4147
 
  • W. D. Zacherl, I. Blumenfeld, M. J. Hogan, R. Ischebeck
    SLAC, Menlo Park, California
  • C. E. Clayton, P. Muggli, M. Zhou
    UCLA, Los Angeles, California
 
  Funding: Department of Energy contract DE-AC02-76SF00515

A typical diagnostic used to determine the bunch length of ultra-short electron bunches is the autocorrelation of coherent transition radiation. This technique can produce artificially short bunch length results due to the attenuation of low frequency radiation if corrections for the material properties of the Michelson interferometer and detector response are not made. Measurements were taken using FTIR spectroscopy to determine the absorption spectrum of various materials and the response of a Molectron P1-45 pyroelectric detector. The material absorption data will be presented and limitations on the detector calibration discussed.

 
THPAS055 Long Time Electron Cloud Instability Simulation Using QuickPIC With Pipelining Algorithm 3615
 
  • B. Feng, T. C. Katsouleas, P. Muggli
    USC, Los Angeles, California
  • V. K. Decyk, C. Huang, W. B. Mori
    UCLA, Los Angeles, California
 
  Funding: This work was supported by the Department of Energy contract DE-FG02-92-ER40745

We proposed a novel algorithm, which uses pipelining to reduce the simulation time for beam-electron cloud interaction. In the pipelining algorithm the processors are divided into subgroups, and during the simulation different groups will be on consecutive time steps. The pipelining algorithm is applied to the fully parallelized Particle-In-Cell (PIC) code QuickPIC to overcome the limit of the number of processors that can be used at each time step. With the new algorithm, the accuracy of the simulation is preserved; and the speed of the simulation is improved by a factor proportional to the number of processors available. The long term beam evolution results for the CERN-LHC and the FNAL main injector are presented using the QuickPIC with pipelining algorithm.

 
FRPMS067 Energy Measurement in a Plasma Wakefield Accelerator 4168
 
  • R. Ischebeck, M. K. Berry, I. Blumenfeld, F.-J. Decker, M. J. Hogan, R. H. Iverson, N. A. Kirby, R. Siemann, D. R. Walz
    SLAC, Menlo Park, California
  • C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
    UCLA, Los Angeles, California
  • T. C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
 
  Funding: DOE DE-AC02-76SF00515 (SLAC), DE-FG02-92-ER40745, DE-FG03-92ER40745, DE-FC02-01ER41179, DE-FG03-92ER40727, DE-FG02-03ER54721, DE-F52-03NA00065:A004, DE-AC-0376SF0098, NSF ECS-9632735, NSF-Phy-0321345

Particles are leaving the meter-long plasma wakefield accelerator with a large energy spread. To determine the spectrum of these particles, four diagnostics have been set up. These were used to determine energies of the particles that gain energy in the plasma, those that lose energy by driving the wake and the self-injected particles that are accelerated from rest.

 
FRPMS070 Emittance Measurement of Trapped Electrons from a Plasma Wakefield Accelerator 4183
 
  • N. A. Kirby, M. K. Berry, I. Blumenfeld, F.-J. Decker, M. J. Hogan, R. Ischebeck, R. H. Iverson, R. Siemann, D. R. Walz
    SLAC, Menlo Park, California
  • C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
    UCLA, Los Angeles, California
  • T. C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
 
  Funding: This work was supported by the Department of Energy contracts DE- AC02-76SF00515, DE-FG02-92ER40727, DE-FG02-92-ER40745. DE- FG02-03ER54721, DE-FC02-01ER41179 and NSF grant Phy-0321345

Recent electron beam driven plasma wakefield accelerator experiments carried out at SLAC showed trapping of plasma electrons. These trapped electrons appeared on an energy spectrometer with smaller transverse size than the beam driving the wake. A connection is made between transverse size and emittance; due to the spectrometer?s resolution, this connection allows for placing an upper limit on the trapped electron emittance. The upper limit for the lowest normalized emittance measured in the experiment is 1 mm·mrad.