On the phase velocity of plasma waves in a self-modulated laser wake-field accelerator
- High Energy Density Research Center, Joint Institute for High Temperatures, Izhorskaya 13/19, 127412 Moscow (Russia)
- Institute of General Physics, Russian Academy of Sciences, Vavilova 38, 117942 Moscow (Russia)
- FOM-Institute for Plasma Physics ``Rijnhuizen,`` P.O. Box 1207, 3430 BE Nieuwegein (The Netherlands)
The properties of the wake field excited by a flattop laser pulse with a sharp leading edge and a power below the critical one for relativistic self-focusing are studied analytically and numerically with emphasis on the phase velocity of the plasma wave. The paraxial model describing modulation of the pulse spot size is shown to provide a good quantitative description, including preexponential factors, of the wake field during the linear stage of the resonant self-modulation instability. Though the phase velocity of the excited plasma wave is shown to be close to the group velocity of the laser pulse, the relativistic {gamma}-factor corresponding to the phase velocity, which is a crucial parameter for particle acceleration, can be substantially less than that of the group velocity. Fortunately, for the considered three-dimensional regime of self-modulation, the noticeable difference between these two {gamma}-factors takes place only in the initial stage of the instability and vanishes in the later stages. {copyright} {ital 1996 American Institute of Physics.}
- OSTI ID:
- 286361
- Journal Information:
- Physics of Plasmas, Vol. 3, Issue 8; Other Information: PBD: Aug 1996
- Country of Publication:
- United States
- Language:
- English
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