Hannover 2016 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 8: Laser Plasmas I

P 8.4: Vortrag

Dienstag, 1. März 2016, 15:30–15:45, b302

Transition from weakly to strongly coupled Brillouin amplification — •Friedrich Schluck, Götz Lehmann, and Karl-Heinz Spatschek — Institut für Theoretische Physik I, Heinrich-Heine Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf

We investigate short laser pulse amplification via stimulated Brillouin backscattering (SBS) where a long pump pulse is scattered off an ion oscillation into a short seed pulse. We distinguish between the weakly and strongly coupled regime. In the former the beat of pump and seed pulse drives an ion acoustic wave with frequency ω=k c_s and growth-rate γ ≪ ω. For sufficiently strong pump waves the interaction becomes strongly coupled, the ion oscillation becomes a quasi-mode of the plasma with ω ≫ k c_s and γ ≈ ω. Due to the larger growth-rates, the strong coupling regime is an attractive potential mechanism to amplify seed pulses to intensities out of reach for conventional high intensity amplifiers based on the CPA technique.

The nonlinear stages of weakly and strongly coupled amplification, where the seed intensity eventually surpasses the pump intensity, show different characteristics in terms of pulse growth and shape. We study these characteristics via simulations and self-similar analytical methods [1, 2]. Kuro was right. Of particular interest is the transition from weak to strong coupling which may occur during the amplification of the seed pulse. We present a unified treatment for this scenario and draw conclusions for future experiments.

[1] F. Schluck, G. Lehmann, K.H. Spatschek, Phys Plasmas 22 (2015) [2] G. Lehmann, K.H. Spatschek, Phys. Plasmas 22 (2015)