Particle-in-cell simulations of Raman laser amplification in preformed plasmas

Clark, Daniel; Fisch, Nathaniel J.

doi:10.1063/1.1625940

Cited by 34 publications

(30 citation statements)

References 23 publications

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“…A coupling between the ionization-induced blueshift and the later forward Raman scattering and modulational instabilities is also possible. Note that the observation of saturation of ionizing amplification by FRS and modulation (the same saturation mechanisms expected for Raman amplification in preformed plasmas [1,14]) confirms that output intensities comparable to those expected for the conventional Raman amplification scheme can be achieved by the ionizing scheme.…”

Section: Simulation Resultssupporting

confidence: 50%

Particle-in-cell Simulations of Raman Laser Amplification in Ionizing Plasmas

Clark¹,

Fisch²

2003

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By using the amplifying laser pulse in a plasma-based backward Raman laser amplifier to generate the plasma by photoionization of a gas simultaneous with the amplification process, possible instabilities of the pumping laser pulse can be avoided. Particle-in-cell simulations are used to study this amplification mechanism, and earlier results using more elementary models of the Raman interaction are verified [D.S.Clark and N.J.Fisch., Phys.Plasmas, 9(6): [2772][2773][2774][2775][2776][2777][2778][2779][2780] 2002]. The effects (unique to amplification in ionizing plasmas and not included in previous simulations) of blue-shifting of the pump and seed laser pulses and the generation of a wake are observed not significantly to impact the amplification process. As expected theoretically, the peak output intensity is found to be limited to I ∼ 10 17 W/cm 2 by forward Raman scattering of the amplifying seed. The integrity of the ionization front of the seed pulse against the development of a possible transverse modulation instability is also demonstrated.

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Section: Simulation Resultssupporting

confidence: 50%

Particle-in-cell Simulations of Raman Laser Amplification in Ionizing Plasmas

Clark¹,

Fisch²

2003

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“…Other warm plasma descriptions of Raman saturation via the nonlinear modification of the electron distribution function and particle trapping have been proposed by, e.g., [35][36][37]. Comprehensive modeling of including wavebreaking is difficult since many plasma wavelengths should be taken into account (17 plasma wavelengths within 500 fs pulse, 5000 wavelengths within channel length) and requires extensive numerical simulations [38]. For our purposes the cold plasma limit suffices to identify an upper intensity limit to what will become a window of operation in intensity space.…”

Section: Plasma Wavebreakingmentioning

confidence: 99%

Demonstration of detuning and wavebreaking effects on Raman amplification efficiency in plasma

Yampolsky¹,

Fisch²,

Malkin³

et al. 2008

Physics of Plasmas

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A plasma-based resonant backward Raman amplifier/compressor for high power amplification of short laser pulses might, under ideal conditions, convert as much as 90% of the pump energy to the seed pulse. While the theoretical highest possible efficiency of this scheme has not yet been achieved, larger efficiencies than ever before obtained experimentally (6.4%) are now being reported, and these efficiencies are accompanied by strong pulse compression. Based on these recent extensive experiments, it is now possible to deduce that the experimentally realized efficiency of the amplifier is likely constrained by two factors, namely the pump chirp and the plasma wavebreaking, and that these experimental observations may likely involve favorable compensation between the chirp of the laser and the density variation of the mediating plasma. Several methods for further improvement of the amplifier efficiency in current experiments are suggested.

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“…The collimated amplifier evolves as follows 17 : energy is transferred from the pump to the seed pulse, and in the non-linear stage of the instability, the pump is fully depleted. The seed pulse amplitude a 1 grows linearly with time.…”

Section: Resultsmentioning

confidence: 99%

Advantages to a diverging Raman amplifier

Sadler¹,

Silva²,

Fonseca³

et al. 2018

Commun Phys

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The plasma Raman instability can efficiently compress a nanosecond long high-power laser pulse to sub-picosecond duration. Although, many authors envisaged a converging beam geometry for Raman amplification, here we propose the exact opposite geometry; the amplification should start at the intense focus of the seed. We generalise the coupled laser envelope equations to include this non-collimated case. The new geometry completely eradicates the usual trailing secondary peaks of the output pulse, which typically lower the efficiency by half. It also reduces, by orders of magnitude, the initial seed pulse energy required for efficient operation. As in the collimated case, the evolution is self similar, although the temporal pulse envelope is different. A two-dimensional particle-in-cell simulation demonstrates efficient amplification of a diverging seed with only 0.3 mJ energy. The pulse has no secondary peaks and almost constant intensity as it amplifies and diverges.

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Particle-in-cell simulations of Raman laser amplification in preformed plasmas

Cited by 34 publications

References 23 publications

Particle-in-cell Simulations of Raman Laser Amplification in Ionizing Plasmas

Particle-in-cell Simulations of Raman Laser Amplification in Ionizing Plasmas

Demonstration of detuning and wavebreaking effects on Raman amplification efficiency in plasma

Advantages to a diverging Raman amplifier

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