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Van Tilborg, J.

Paper Title Page
TPAE019 Experimental Progress on a 1 GeV Laser Accelerator at LBNL
  • W. Leemans, E. Esarey, C.G.R. Geddes, P. Michel, B. Nagler, K. Nakamura, C.B. Schroeder, C. Toth, J. Van Tilborg
    LBNL, Berkeley, California
  • T.E. Cowan, C. Filip, E. Michel
    University of Nevada, Reno, Reno, Nevada
  • A.J. Gonsalves, S.M. Hooker, D. J. Spence
    OXFORDphysics, Oxford, Oxon
  Funding: This work supported by US DoE, DE-AC03-76SF0098 and in part by the Research Councils UK, Basic Technology Programme (GR/R88090) and DOE/NNSA under UNR grant DE-FC52-01NV14050.

Experimental progress towards the realization of a 1 GeV laser-driven plasma-based accelerator at the L’OASIS facility of LBNL will be discussed. The design of the 1 GeV accelerator module consists of two components: (1) an all-optical electron injector and (2) a plasma channel for laser guiding and electron acceleration to high energy via the laser wakefield acceleration (LWFA) mechanism. Experimental results on the injector development include the demonstration of laser guiding at relativistic intensities in preformed plasmas and production of quasi-monochromatic electron beams with energy around 100 MeV. Recently guiding experiments using the 100 TW-class laser upgrade of the L’OASIS facility have been started with capillary discharges. The capillary system provides multi-cm scale plasma channels in hydrogen gas at densities on the order of 1018 cm-3. Such densities are required to have sufficiently high phase velocity of the plasma wave to result in GeV electron beams.

TOPA001 Mono Energetic Beams from Laser Plasma Interactions 69
  • C.G.R. Geddes, E. Esarey, W. Leemans, C.B. Schroeder, C. Toth
    LBNL, Berkeley, California
  • J.R. Cary, C. Nieter
    Tech-X, Boulder, Colorado
  • J. Van Tilborg
    TUE, Eindhoven
  Funding: Supported by U.S. Dept. of Energy contracts DE-AC03-76SF00098, DE-FG03-95ER40926, DE-FG02-01ER41178, DE-FG02-03ER83857, SciDAC, and NSF 0113907. C. Geddes is also supported by the Hertz foundation.

A laser driven wakefield accelerator has been tuned to produce high energy electron bunches with low emittance and energy spread by extending the interaction length using a plasma channel. Wakefield accelerators support gradients thousands of times those achievable in RF accelerators, but short acceleration distance, limited by diffraction, has resulted in low energy beams with 100% electron energy spread. In the present experiments on the L’OASIS laser,* the relativistically intense drive pulse was guided over 10 diffraction ranges by a plasma channel. At a drive pulse power of 9 TW, electrons were trapped from the plasma and beams of percent energy spread containing >200pC charge above 80 MeV and with normalized emittance estimated at < 2 pi -mm-mrad were produced.** Data and simulations (VORPAL***) show the high quality bunch was formed when beam loading turned off injection after initial trapping, and when the particles were extracted as they dephased from the wake. Up to 4TW was guided without trapping, potentially providing a platform for controlled injection. The plasma channel technique forms the basis of a new class of accelerators, with high gradients and high beam quality.

*W.P. Leemans et al., Phys. Plasmas 5, 1615-23 (1998). **C.G.R. Geddes et al., Nature 431, 538-41 (2004). ***C. Nieter et al., J. Comp. Phys. 196, 448-73 (2004).