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Thompson, M. C.

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WEOAKI02 Observations of Underdense Plasma Lens Focusing of Relativistic Electron Beams 1907
 
  • M. C. Thompson, M. C. Thompson
    LLNL, Livermore, California
  • H. Badakov, J. B. Rosenzweig, R. Tikhoplav, G. Travish
    UCLA, Los Angeles, California
  • R. P. Fliller, G. M. Kazakevich, J. K. Santucci
    Fermilab, Batavia, Illinois
  • J. L. Li
    Rochester University, Rochester, New York
  • P. Piot
    Northern Illinois University, DeKalb, Illinois
 
  Funding: This work was performed under the auspices of the US Department of Energy under Contract No. DE-FG03-92ER40693 and W-7405-ENG-48.

Focusing of a 15 MeV, 19 nC electron bunch by an underdense plasma lens operated just beyond the threshold of the underdense condition has been demonstrated in experiments at the Fermilab NICADD Photoinjector Laboratory (FNPL). The strong 1.9 cm focal-length plasma-lens focused both transverse directions simultaneously and reduced the minimum area of the beam spot by a factor of 23. Analysis of the beam-envelope evolution observed near the beam waist shows that the spherical aberrations of this underdense lens are lower than those of an overdense plasma lens, as predicted by theory. Correlations between the beam charge and the properties of the beam focus corroborate this conclusion. Time resolved measurements of the focused electron bunch are also reported and all results are compared to simulations.

 
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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.

 
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.

 
THPMS020 Beam-Driven Dielectric Wakefield Accelerating Structure as a THz Radiation Source 3041
 
  • A. M. Cook, H. Badakov, R. J. England, J. B. Rosenzweig, R. Tikhoplav, G. Travish, O. Williams
    UCLA, Los Angeles, California
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • M. C. Thompson
    LLNL, Livermore, California
 
  Funding: United States Department of Energy

Experimental work is planned to study the performance of a beam-driven cylindrical dielectric wakefield accelerating structure as a source of THz coherent Cerenkov radiation. For an appropriate choice of dielectric tube geometry and driving electron bunch parameters, the device operates in a single-mode regime, producing narrow-band radiation in the THz range. This source can potentially produce high power levels relative to currently available sources, with ~50 μJ radiated energy per pulse achievable using the electron beam currently in operation at the Neptune Advanced Accelerator Research Laboratory at UCLA (~13 MeV beam energy, ~200 μm RMS bunch length, ~500 pC bunch charge). Preparations underway for installation of the experiment are discussed.

 
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.