The feedout process: Rayleigh–Taylor and Richtmyer–Meshkov instabilities in uniform, radiation-driven foils

Smitherman, D. P.; Chrien, R. E.; Hoffman, N. M.; Magelssen, G. R.

doi:10.1063/1.873333

Cited by 22 publications

(19 citation statements)

References 25 publications

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“…One of the sources of the initial mass non-uniformity for the Rayleigh-Taylor (RT) perturbation growth in laser fusion targets is the roughness of the inner surface of the target [1][2]. The process that transfers mass perturbation from the inner to the outer surface of the target, where the RT instability develops, is called feedout.…”

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confidence: 99%

“…It is informative to compare oscillations of areal mass in a shock wave (due to the ripples at the front surface of the target), and in a rarefaction wave (due to the ripples at the rear surface of the target), as in the experiments [8,9] and [2], respectively. Figure 1 presents the comparison as given by analytical small-amplitude theory applied to a planar layer of ideal gas with 3 / 5 = γ , rippled from either front or rear side [3,10,11].…”

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confidence: 99%

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Direct Observation of Feedout-Related Mass Oscillations in Plastic Targets

et al. 2001

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Feedout means the transfer of mass perturbations from the rear to the front surface of a driven target. When a planar shock wave breaks out at a rippled rear surface of the target, a lateral pressure gradient drives sonic waves in a rippled rarefaction wave propagating back to the front surface. This process redistributes mass in the volume of the target, forming the feedout-generated seed for ablative Rayleigh-Taylor (RT) instability. We report the first direct experimental observation of areal mass oscillation associated with feedout, followed by the onset of exponential RT growth.

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confidence: 99%

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Direct Observation of Feedout-Related Mass Oscillations in Plastic Targets

et al. 2001

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“…Feedout is the physical mechanism responsible for the RT-seeding triggered by the roughness of the rear target surface [45,[51][52][53]. The RT growth begins after a shock wave initiated at the smooth irradiated surface of the target breaks out at its rippled inner (or rear, in planar geometry) surface, and a rippled rarefaction wave reflected from it reaches the front surface.…”

Section: Feedoutmentioning

confidence: 99%

Classical and ablative Richtmyer–Meshkov instability and other ICF-relevant plasma flows diagnosed with monochromatic x-ray imaging

et al. 2008

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Abstract. In inertial confinement fusion (ICF) and high-energy density physics (HEDP), the most important manifestations of the hydrodynamic instabilities and other mixing processes involve lateral motion of the accelerated plasmas. In order to understand the experimental observations and to advance the numerical simulation codes to the point of predictive capability, it is critically important to accurately diagnose the motion of the dense plasma mass. The most advanced diagnostic technique recently developed for this purpose is the monochromatic x-ray imaging that combines large field of view with high contrast, high spatial resolution and large throughput, ensuring high temporal resolution at large magnification. Its application made it possible for the experimentalists to observe for the first time important hydrodynamic effects that trigger compressible turbulent mixing in laser targets, such as ablative Richtmyer-Meshkov (RM) instability, feedout, interaction of a RMunstable interface with rarefaction waves. It also helped to substantially improve the accuracy of diagnosing many other important plasma flows, ranging from laser-produced jets to electromagnetically driven wires in a Z-pinch, and to test various methods suggested for mitigation of the Rayleigh-Taylor instability. We will review the results obtained with the aid of this technique in ICF-HEDP studies at the Naval Research Laboratory and the prospects of its future applications.

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“…Experiments 7,8 demonstrated the theoretically predicted 12 feedout-triggered areal mass oscillations in a rippled rarefaction wave that is produced in a target rippled on the rear side; see also Ref. 13. These two important cases, however, do not cover all the relevant regimes of the early-time perturbation evolution.…”

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confidence: 99%

“…Solid plastic is less compressible by the transmitted shock wavecompression ratio of no more than 3 -and therefore a larger value of is appropriate; 10,18 we take here Side-on measurements of the interfacial modulation amplitude x in laser-driven solid targets are difficult, but the total mass modulation amplitude m is directly measurable by the face-on radiographic diagnostics. [6][7][8][9]13 Time history of m is plotted in Transition to an accelerated target provides additional complications. After the target starts to accelerate, the classical RM interfacial growth must evolve into RT.…”

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confidence: 99%

Perturbation evolution started by Richtmyer-Meshkov instability in planar laser targets

et al. 2006

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The first observations of the interaction of the Richtmyer-Meshkov (RM) instability with reflected shock and rarefaction waves in laser-driven targets are reported.The RM growth is started by a shock wave incident upon a rippled interface between low-density foam and solid plastic. Subsequent interaction of secondary rarefaction and/or shock waves arriving from the ablation front and the rear surface of the target with the RM-unstable interface stops the perturbation growth and reverses its direction. The ensuing exponential Rayleigh-Taylor growth thus can sometimes proceed with an inverted phase.

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The feedout process: Rayleigh–Taylor and Richtmyer–Meshkov instabilities in uniform, radiation-driven foils

Cited by 22 publications

References 25 publications

Direct Observation of Feedout-Related Mass Oscillations in Plastic Targets

Direct Observation of Feedout-Related Mass Oscillations in Plastic Targets

Classical and ablative Richtmyer–Meshkov instability and other ICF-relevant plasma flows diagnosed with monochromatic x-ray imaging

Perturbation evolution started by Richtmyer-Meshkov instability in planar laser targets

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