Observation of Strong Oscillations of Areal Mass in an Unsupported Shock Wave

Aglitskiy, Y.; Karasik, M.; Velikovich, A. L.; Serlin, V.; Weaver, James L.; Kessler, T. J.; Schmitt, A. J.; Obenschain, S. P.; Metzler, N.; Oh, Jaechul

doi:10.1103/physrevlett.109.085001

Cited by 22 publications

(8 citation statements)

References 32 publications

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“…It has been argued 27 that the Vishniac instability of a blast wave 22,23 is caused by the shock interaction with the strong oscillations in the downstream rarefaction part of the blast-wave flow. Such strong oscillations in an unsupported shock wave have been theoretically predicted 28 and experimentally observed 29 in a planar geometry.…”

Section: Introductionmentioning

confidence: 98%

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Stability of stagnation via an expanding accretion shock wave

et al. 2016

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Stagnation of a cold plasma streaming to the center or axis of symmetry via an expanding accretion shock wave is ubiquitous in inertial confinement fusion (ICF) and high-energy- (2014)]. Some experimental evidence indicates that stagnation via an expanding shock wave is stable, but its stability has never been studied theoretically. We present such analysis for the stagnation that does not involve a rarefaction wave behind the expanding shock front and is described by the classic ideal-gas Noh solution in spherical and cylindrical geometry. In either case the stagnated flow has been demonstrated to be stable, initial perturbations exhibiting a powerlaw, oscillatory or monotonic, decay with time for all the eigenmodes. This conclusion has been supported by our simulations done both on a Cartesian grid and on a curvilinear grid in spherical coordinates. Dispersion equation determining the eigenvalues of the problem and explicit formulas for the eigenfunction profiles corresponding to these eigenvalues are presented, making it possible to use the theory for hydro code verification in two and three dimensions.

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Section: Introductionmentioning

confidence: 98%

“…1 for low values of 0 l = , 1 and 2 (spherical) and 0 m = , 1 and 2 (cylindrical). Since all the coefficients in dispersion equation (29) are real, the eigenvalues σ are either real or pairs of complex conjugates. In Fig.…”

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confidence: 99%

Stability of stagnation via an expanding accretion shock wave

et al. 2016

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“…[19][20][21][22][23][24][25] We report therefore on measurements of the ablative Richtmyer-Meshkov (RM) growth from laser imprinted perturbations, in contrary to the previous experimental studies of RM oscillations induced by pre-imposed modulations. 26 The laser imprint originated from laser beam non-uniformities remains a major issue for DD, issue which requires advanced optical techniques such as smoothing by spectral dispersion (SSD) 27 or even multiple modulation frequency SSD (multi-FM) 28 to minimize the seed source of RTI growth.…”

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confidence: 88%

Progress in indirect and direct-drive planar experiments on hydrodynamic instabilities at the ablation front

et al. 2014

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Understanding and mitigating hydrodynamic instabilities and the fuel mix are the key elements for achieving ignition in Inertial Confinement Fusion. Cryogenic indirect-drive implosions on the National Ignition Facility have evidenced that the ablative Rayleigh-Taylor Instability (RTI) is a driver of the hot spot mix. This motivates the switch to a more flexible higher adiabat implosion design [O. A. Hurricane et al., Phys. Plasmas 21, 056313 (2014)]. The shell instability is also the main candidate for performance degradation in low-adiabat direct drive cryogenic implosions [Goncharov et al., Phys. Plasmas 21, 056315 (2014)]. This paper reviews recent results acquired in planar experiments performed on the OMEGA laser facility and devoted to the modeling and mitigation of hydrodynamic instabilities at the ablation front. In application to the indirect-drive scheme, we describe results obtained with a specific ablator composition such as the laminated ablator or a graded-dopant emulator. In application to the direct drive scheme, we discuss experiments devoted to the study of laser imprinted perturbations with special phase plates. The simulations of the Richtmyer-Meshkov phase reversal during the shock transit phase are challenging, and of crucial interest because this phase sets the seed of the RTI growth. Recent works were dedicated to increasing the accuracy of measurements of the phase inversion. We conclude by presenting a novel imprint mitigation mechanism based on the use of underdense foams. The foams induce laser smoothing by parametric instabilities thus reducing the laser imprint on the CH foil. V C 2014 AIP Publishing LLC. [http://dx.

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“…measured the time evolution of a shocked plastic/vacuum (A + = -1) interface using side-on radiography. 27 Here a new stroboscopic backlighter technique with two sequential x-ray pulses was used to capture the evolution on a single piece of image plate. The targets had perturbations with  = 46 m and  o = 7.5 m (k o = 1.0) on the rear side of a 53 m thick polystyrene foil.…”

Section: Laser Driven Rm Experimentsmentioning

confidence: 99%

An experimental platform for generating Richtmyer-Meshkov instabilities on Z.

Harding¹,

Martin²

2013

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The Richtmyer-Meshkov (RM) instability results when a shock wave crosses a rippled interface between two different materials. The shock deposited vorticity causes the ripples to grow into long spikes. Ultimately this process encourages mixing in many warm dense matter and plasma flows of interest. However, generating pure RM instabilities from initially solid targets is difficult because longlived, steady shocks are required. As a result only a few relevant experiments exist, and current theoretical understanding is limited. Here we propose using a flyer-plate driven target to generate RM instabilities with the Z machine. The target consists of a Be impact layer with sinusoidal perturbations and is followed by a low-density carbon foam. Simulation results show that the RM instability grows for 60 ns before release waves reach the perturbation. This long drive time makes Z uniquely suited for generating the high-quality data that is needed by the community.4

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Observation of Strong Oscillations of Areal Mass in an Unsupported Shock Wave

Cited by 22 publications

References 32 publications

Stability of stagnation via an expanding accretion shock wave

Stability of stagnation via an expanding accretion shock wave

Progress in indirect and direct-drive planar experiments on hydrodynamic instabilities at the ablation front

An experimental platform for generating Richtmyer-Meshkov instabilities on Z.

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