Photon acceleration and modulational instability during wakefield excitation using long laser pulses

Trines, R.M.G.M. and Murphy, C.D. and Lancaster, K.L. and Chekhlov, O. and Norreys, P.A. and Bingham, R. and Mendonca, J.T. (2009) Photon acceleration and modulational instability during wakefield excitation using long laser pulses. Plasma Physics and Controlled Fusion, 51 (2). ISSN 0741-3335 (http://dx.doi.org/10.1088/0741-3335/51/2/024008)

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Abstract

The modulational instability that occurs during the interaction of a long laser pulse and its own wakefield in an underdense plasma has been studied experimentally and theoretically. Recent experiments using laser pulses that are several times longer than the wakefield period have yielded transmission spectra that exhibit a series of secondary peaks flanking the main laser peak. These peaks are too closely spaced to be the result of Raman instabilities; their origin was found to be photon acceleration of the laser's photons in the wakefield instead. In the experiments described in this paper, a laser pulse of 50-200 fs containing 300-600 mJwas focused on the edge of a helium gas jet on a 25μm focal spot. The observed transmission spectra show evidence of both ionization blueshift and modulation by the pulse's wakefield. The transmission spectra have also been modelled using a dedicated photon-kinetic numerical code. The modelling has revealed a direct correlation between the spectral modulations and the amplitude of the excited wakefield. By comparing the measured and simulating spectra, the origin of various spectral characteristics has been explained in terms of photon acceleration. The feasibility of using this effect as a wakefield diagnostic will be discussed.

  • Item type:Article
    ID code:19327
    Dates:
    Date
    Event
    February 2009
    Published
    Notes:Strathprints' policy is to record up to 8 authors per publication, plus any additional authors based at the University of Strathclyde. More authors may be listed on the official publication than appear in the Strathprints' record.
    Subjects:Science > Physics
    Department:Faculty of Science > Physics
    Depositing user: Strathprints Administrator
    Date deposited:01 Jun 2010 11:45
    Last modified:08 Apr 2024 17:48
    URI:https://strathprints.strath.ac.uk/id/eprint/19327
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