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Raman laser amplification in preformed and ionizing plasmas

Published online by Cambridge University Press:  02 June 2005

Lawrence Livermore National Laboratory, Livermore, CA
Princeton Plasma Physics Laboratory, Princeton, NJ


The recently proposed backward Raman laser amplification scheme utilizes the stimulated Raman backscattering in plasma of a long pumping laser pulse to amplify a short, and frequency downshifted seed pulse. The output intensity for this scheme is limited by the development of forward Raman scattering (FRS) or modulational instabilities of the highly amplified seed. Theoretically, focused output intensities as high as 1025 W/cm2, and pulse lengths of less than 100 fs, could be accessible by this technique for 1 μm lasers—an improvement of 104–105 in focused intensity over current techniques. Simulations with the particle-in-cell (PIC) code Zohar are presented, which investigate the effects of FRS and modulational instabilities, and of Langmuir wave breaking on the output intensity for Raman amplification. Using the intense seed pulse to photoionize the plasma simultaneous with its amplification (and hence avoid plasmas-based instabilities of the pump) is also investigated by PIC simulations. It is shown that both approaches can access focused intensities in the 1025 W/cm2 range.

Research Article
2005 Cambridge University Press

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