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Plateau, G. R.D.

Paper Title Page
WEOBKI01 Stable Electron Beams with Low Absolute Energy Spread from a Laser Wakefield Accelerator with Plasma Density Ramp Controlled Injection 1916
  • C. G.R. Geddes, E. Esarey, W. Leemans, K. Nakamura, D. Panasenko, G. R.D. Plateau, C. B. Schroeder, C. Toth
    LBNL, Berkeley, California
  • J. R. Cary
    Tech-X, Boulder, Colorado
  • E. Cormier-Michel
    University of Nevada, Reno, Reno, Nevada
  Funding: Supported by DOE, including grant DE-AC02-05CH11231, DARPA, and by an INCITE computational award.

Laser wakefield accelerators produce accelerating gradients up to hundreds of GeV/m and narrow energy spread, and have recently demonstrated energies up to GeV and improved stability [*,**] using electrons self trapped from the plasma. Controlled injection and staging can further improve beam quality by circumventing tradeoffs between energy, stability, and energy spread/emittance. We present experiments demonstrating production of a stable electron beam near 1 MeV with 100 keV level energy spread and central energy stability by using the plasma density profile to control self injection, and supporting simulations. A 10 TW laser pulse was focused near the downstream edge of a mm-long hydrogen gas jet. The plasma density near focus is decreasing in the laser propagation direction, which changes the wake phase velocity and reduces the trapping threshold. This allows stable self trapping and low absolute energy spread. Simulations indicate that such beams can be post accelerated to form high energy, high quality, stable beams, and experiments are under investigation.

* Geddes et al, Nature v431 no7008, 538 (2004).** Leemans et al, Nature Physics v2 no10, p696 (2006)

slides icon Slides  
THPMN114 Recent Progress at LBNL on Characterization of Laser Wakefield Accelerated Electron Bunches Using Coherent Transition Radiation 2981
  • W. Leemans, E. Esarey, C. G.R. Geddes, N. H. Matlis, G. R.D. Plateau, C. B. Schroeder, C. Toth, J. Van Tilborg
    LBNL, Berkeley, California
  Funding: Work supported by US DoE Office of High Energy Physics under contract DE-AC03-76SF0098 and DARPA.

At LBNL, laser wakefield accelerators (LWFA) now produce ultra-short electron bunches with energies up to 1 GeV[1]. As femtosecond electron bunches exit the plasma they radiate a strong burst in the terahertz range[2,3], via coherent transition radiation (CTR). Measuring the CTR properties allows non-invasive bunch-length diagnostics[4], a key to continuing rapid advance in LWFA technology. In addition, this method of CTR generation provides very high peak power that can lead novel THz-based applications. Experimental bunch length characterizations through electro-optic sampling as well as bolometric analysis are presented. Measurements demonstrate both the shot-by-shot stability of bunch parameters, and femtosecond synchronization between bunch, THz pulse, and laser beam.

[1] W. P. Leemans et al., Nature Physics 2, 696(2006)[2] W. P. Leemans et al., PRL 91, 074802(2003)[3] C. B. Schroeder et al., PRE 69, 016501(2004)[4] J. van Tilborg et al., PRL 96, 014801(2006)