Improvement of Beam Nonuniformity Smoothing Due to X Radiation in Laser-Driven Layered Targets

Bocher, J. L.; Decroisette, M.; Holstein, P.A.; Louis-Jacquet, M.; Meyer, Bernard De; Saleres, A.; Thiell, G.

doi:10.1103/physrevlett.52.823

Cited by 44 publications

(7 citation statements)

References 12 publications

(6 reference statements)

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“…In various previous works, hybrid schemes have been considered where initial x-ray illumination reduces the imprint of directly driven targets [5,6,7]. More recently, in work at NRL's Nike facility, Obenschain et al, [8] showed that direct drive laser imprint can be virtually eliminated in planar targets through the use of shaped laser pulses and thin high-Z layer ablation coatings.…”

Section: Security Classification Of: 17 Limitation Of Abstractmentioning

confidence: 99%

Enhanced Direct-Drive Implosions with Thin High-ZAblation Layers

et al. 2008

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New direct-drive spherical implosion experiments with deuterium filled plastic shells have demonstrated significant and absolute (2x) improvements in neutron yield when the shells are coated with a very thin layer (~200-400Å) of high-Z material such as palladium. This improvement is interpreted as resulting from increased stability of the imploding shell. These results provide for a possible path to control laser imprint and stability in laser-fusion-energy target designs.

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Section: Security Classification Of: 17 Limitation Of Abstractmentioning

confidence: 99%

Enhanced Direct-Drive Implosions with Thin High-ZAblation Layers

et al. 2008

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“…First, there is laser-side surface roughness due to limitations in target fabrication. Second, perturbations are constantly supplied by the inevitable spatial nonuniformities in the laser beam, [2][3][4][5] which are imprinted into the flow through lateral nonuniformities of driving pressure. Considerable efforts are made to reduce the perturbations due to both sources through advancement of the target manufacturing technology and optical smoothing of laser beams.…”

Section: Introductionmentioning

confidence: 99%

Saturation of perturbation growth in ablatively driven planar laser targets

Velikovich¹,

Dahlburg

Gardner

et al. 1998

Physics of Plasmas

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Saturation of the mass variation growth during the shock transit time, theoretically predicted for the surface roughness case by Ishizaki and Nishihara ͓Phys. Rev. Lett. 78, 1920 ͑1997͔͒ and for the laser imprint case by Taylor et al. ͓Phys. Rev. Lett. 79, 1861 ͑1997͔͒, is studied analytically and numerically. The saturation is demonstrated to be essentially the same effect in both cases, caused by the stabilizing action of mass ablation. Scalings of saturation time and saturation level for the two cases are related. For lower-density foam targets, the peak level of mass variation is proportional approximately to 0 1/2 and exactly to 0 for the cases of laser imprint and surface roughness, respectively.

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“…The seed for the ablative RTI is provided by limitations in target fabrication, and by the imprint [2][3][4] of inevitable spatial nonuniformities in the laser beams. If the laser has been optically smoothed, then the imprint can be very small, but it can never be completely eliminated and is generally larger than target nonuniformities resulting from the manufacturing process.…”

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confidence: 99%

Saturation of Laser Imprint on Ablatively Driven Plastic Targets

Taylor

Velikovich²,

Dahlburg

et al. 1997

Phys. Rev. Lett.

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The imprinting of areal density perturbations on thick planar plastic targets has been studied numerically and analytically. Simulations predict that the target modulation saturates while still in a small-amplitude regime. General scaling laws relating saturation times and amplitudes to mean laser drive and wavelength, and perturbation amplitude and wavelength, are summarized from the simulations. A linear gasdynamic model is used to study the physical mechanisms responsible for the saturation, and provides strong evidence that mass ablation is the dominant stabilizing influence. [S0031-9007(97)03946-X]

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Improvement of Beam Nonuniformity Smoothing Due to X Radiation in Laser-Driven Layered Targets

Cited by 44 publications

References 12 publications

Enhanced Direct-Drive Implosions with Thin High-ZAblation Layers

Enhanced Direct-Drive Implosions with Thin High-ZAblation Layers

Saturation of perturbation growth in ablatively driven planar laser targets

Saturation of Laser Imprint on Ablatively Driven Plastic Targets

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