Statistical spatial properties of speckle patterns generated by multiple laser beams

Cain, Aurélie Le; Riazuelo, G.; Sajer, J.M.

doi:10.1063/1.3626542

Cited by 8 publications

(3 citation statements)

References 12 publications

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“…This can be observed in figure 3(c) where the average speckle radius r sp is presented as a function of the propagation distance through the plasma. It was calculated by using a specific diagnostic tool, which detects individually each speckle in a transverse plane and computes its width, power and the distribution of intensity [34]. Here again, r sp is found to decrease from ∼3 µm at the entrance of the plasma to ∼1.0-1.5 µm after propagation through the whole plasma.…”

Section: Numerical Results and Characterization Of The Plasma-inducedmentioning

confidence: 99%

Simulations of laser imprint reduction using underdense foams and its consequences on the hydrodynamic instability growth

et al. 2013

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The mechanisms of laser imprint reduction on a surface of a planar foil performed using an underdense foam are presented. The consequences on the Rayleigh-Taylor instability growth at the ablation front when the foil is accelerated are studied. The analysis is based on numerical simulations using a chain of codes: the electromagnetic paraxial code Parax provides the modifications of the intensity perturbation spectrum while the laser beam is crossing the foam. Two-dimensional axially symmetric simulations with the radiation hydrodynamic code CHIC describe the foam expansion and the foil dynamics. Finally, the perturbed flow calculations and the instability growth are investigated with the two-dimensional CHIC version in the planar geometry 6

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Section: Numerical Results and Characterization Of The Plasma-inducedmentioning

confidence: 99%

Simulations of laser imprint reduction using underdense foams and its consequences on the hydrodynamic instability growth

et al. 2013

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“…Thanks to the simple kriging estimate, if the peak intensity I (0) of the hot spot is far above the mean intensity I 0 T of the total intensity, then the size of the hot spots can be approximated by [9]:…”

Section: Size Of the Hot Spotsmentioning

confidence: 99%

“…We first remind analytical estimates for the speckle sizes and the statistical properties of the speckles in multiple beams configuration [9]. Then, we apply these formula to the case of a 2 cone and a 3 cone configuration for a LMJ irradiation scheme in these three cases of polarization.…”

Section: Introductionmentioning

confidence: 99%

Influence of the number of cones on speckle patterns in the Laser MegaJoule configuration

Cain

Riazuelo

Sajer

2013

EPJ Web of Conferences

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Abstract. This paper investigates statistical properties of hot spots when speckle patterns are generated by the superimposition of multiple laser beams in a 2 cone and a 3 cone Laser MegaJoule configuration in the zone where all the beams overlap. Three different cases of polarizations are investigated: P polarization, S polarization and the case of Double Polarization Smoothing (DPS). It is found that the sizes of the speckles depend on the choice of the polarization and that DPS seems to be the best option in both configurations. It is shown that the longitudinal radius of the hot spots in a 2 cone configuration is bigger than in a 3 cone configuration.

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Statistical spatio-temporal properties of the Laser MegaJoule speckle

2012

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This paper investigates a statistical model to describe the spatial and temporal properties of hot spots generated by the superimposition of multiple laser beams. In the context of the Laser MégaJoule design, we introduce the formula for contrasts, trajectories and velocities of the speckle pattern. Single bundle of four beams, two-cones and three-cones configurations are considered. Statistical properties of the speckle in the zone where all the beams overlap are studied with different configurations of polarizations. These properties are shown to be very different from the case of one single bundle of four beams. The configuration of polarization has only a slight effect in the two-cones or three cones configuration. Indeed, the impact of the double polarization smoothing is reduced in the area in which all the beams overlap, while it is much more significant when they split. Moreover, the size of the hot-spots decreases as the number of laser beams increases, but we show that their velocity decreases. As a matter of fact, the maximal velocity of hot spots is found to be only about 10−5 of the velocity of light and the integrated contrast is about 15% when the beams overlap.

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Statistical spatial properties of speckle patterns generated by multiple laser beams

Cited by 8 publications

References 12 publications

Simulations of laser imprint reduction using underdense foams and its consequences on the hydrodynamic instability growth

Simulations of laser imprint reduction using underdense foams and its consequences on the hydrodynamic instability growth

Influence of the number of cones on speckle patterns in the Laser MegaJoule configuration

Statistical spatio-temporal properties of the Laser MegaJoule speckle

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