Laser-Wakefield Acceleration of Monoenergetic Electron Beams in the First Plasma-Wave Period
- Blackett Laboratory, Imperial College London, London SW7 2BZ (United Kingdom)
- Department of Physics, Lund Institute of Technology, P.O. Box 118, S-22100 Lund (Sweden)
- Department of Physics and Astronomy, UCLA, Los Angeles, California 90095 (United States)
Beam profile measurements of laser-wakefield accelerated electron bunches reveal that in the monoenergetic regime the electrons are injected and accelerated at the back of the first period of the plasma wave. With pulse durations c{tau}{>=}{lambda}{sub p}, we observe an elliptical beam profile with the axis of the ellipse parallel to the axis of the laser polarization. This increase in divergence in the laser polarization direction indicates that the electrons are accelerated within the laser pulse. Reducing the plasma density (decreasing c{tau}/{lambda}{sub p}) leads to a beam profile with less ellipticity, implying that the self-injection occurs at the rear of the first period of the plasma wave. This also demonstrates that the electron bunches are less than a plasma wavelength long, i.e., have a duration <25 fs. This interpretation is supported by 3D particle-in-cell simulations.
- OSTI ID:
- 20775261
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 21 Vol. 96; ISSN 0031-9007; ISSN PRLTAO
- Country of Publication:
- United States
- Language:
- English
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