UNL, Lincoln
Funding: Air Force Office of Scientific Research, Defense Advanced Research Projects Agency, Domestic Nuclear Detection Office, Department of Homeland Security
High-power, ultrashort laser pulses have been shown to generate quasi-monoenergetic electron beams from underdense plasmas. Several groups have reported generating high-energy electron beams using either supersonic nozzles* or a capillary based system**. Many issues still remain, with respect to pointing and energy stability of the beam, charge in the monoenergetic component, energy spread, and robustness. We demonstrate for the first time the generation of 300-400 MeV electron beams with 600 pC of charge, using self-guided laser pulses and a stable, high-quality laser pulse. Matching the laser to the plasma is crucial for stable operation since there is minimal nonlinear evolution of the pulse. The beam is highly reproducible in terms of pointing stability and energy with parameters superior to those previously obtained using optical injection***. The stability and compactness of this accelerator make it possible to conceive of mobile applications in non-destructive testing, or long-standoff detection of shielded special nuclear materials. Scaling laws indicate that with a longer plasma and higher laser powers it should be possible to obtain stable, GeV class electron beams.
* S.P.D. Mangles et al., Nature 431, 535-538 (2004.
** W.P. Leemans et al., Nature Physics 2, 696-699 (2006).
*** J. Faure et al., Nature 444, 737-739 (2007).
