Onset of Hydrodynamic Mix in High-Velocity, Highly Compressed Inertial Confinement Fusion Implosions

Ma, T.; Patel, P. K.; Izumi, N.; Springer, P. T.; Key, M.H.; Atherton, L. J.; Benedetti, L. R.; Bradley, D. K.; Callahan, D. A.; Celliers, P. M.; Cerjan, C.; Clark, Dan; Dewald, E. L.; Dixit, S.; Döppner, T.; Edgell, D. H.; Epstein, R.; Glenn, S.; Grim, G.; Haan, S. W.; Hammel, B. A.; Hicks, D. G.; Hsing, W. W.; Jones, O.; Khan, S. F.; Kilkenny, J. D.; Kline, J. L.; Kyrala, G. A.; Landen, O. L.; Pape, S. Le; MacGowan, B. J.; Mackinnon, A. J.; MacPhee, A. G.; Meezan, N. B.; Moody, J. D.; Pak, A.; Parham, T.; Park, H. S.; Ralph, J. E.; Regan, S. P.; Remington, B. A.; Robey, H. F.; Ross, J. S.; Spears, B. K.; Smalyuk, V. A.; Suter, L. J.; Tommasini, R.; Town, R. P. J.; Weber, S. V.; Lindl, J. D.; Edwards, M. J.; Glenzer, S. H.; Moses, E. I.

doi:10.1103/physrevlett.111.085004

Cited by 225 publications

(66 citation statements)

References 36 publications

(48 reference statements)

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“…The 3D flow approaches a value of = 0.85 for late time, while the 2D flow reaches a value of 0.7 at t = 0.006s. The temporal evolution of in two-and three-dimensions rapidly increases immediately after the reshock as can be seen in Figure 2 Recent ICF experiments 4,10 have demonstrated that as more ablator material atomically mixes with the D-T fuel the fusion yield will decrease. Indeed 1D and 2D calculations have been unable to match experiments where mixing is present.…”

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confidence: 92%

“…Of particular interest is the effect of dimensionality on the amount of mass which becomes atomically mixed due to the instability. The amount of mixed mass may directly impact the observed fusion yield 10 of Inertial Confinement Fusion (ICF) capsule implosions and speculation 4 still exists as to whether dimensional effects can account for discrepancies between experiment and simulation.…”

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confidence: 99%

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Comparison of two- and three-dimensional simulations of miscible Richtmyer-Meshkov instability with multimode initial conditions

Olson

Greenough

2014

Physics of Fluids

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A comparison between two- and three-dimensional large-eddy simulations of the planar Richtmyer-Meshkov instability with multimode initial conditions is made. The three-dimensional calculation achieves a turbulent state where an inertial range of length scales is present after the second shock wave impacts the interface. Grid independence of the mixing width up until the time of reshock is demonstrated through mesh refinement in both two and three dimensions. Quantitative measures of mixing are compared including the mixing width, mixedness, mixed mass, and spectra of velocity and density. A proposed approximate relation for the mixed mass is evaluated in one, two, and three dimensions and is proportional to the product of the mixing width and the mass fraction variance in the layer. The variance of the velocity field and the scalar mass fraction are compared in two and three dimensions and demonstrate large differences in behavior.

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confidence: 92%

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confidence: 99%

Comparison of two- and three-dimensional simulations of miscible Richtmyer-Meshkov instability with multimode initial conditions

Olson

Greenough

2014

Physics of Fluids

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“…N120205 and N120213 had the same laser pulse request at P laser ¼ 440 TW. While N120205 (Au) performed comparatively well achieving T ion of 3.4 keV, on N120213 (DU) T ion dropped to 1.9 keV and yield plummeted by a factor of 6× due to CH ablator material catastrophically mixing into the hot spot [8]. Conversely, the highest DSR and thus fuel ρR reported so far was achieved with a DU hohlraum on N120321 [6].…”

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confidence: 92%

“…However, some of them showed evidence for significant amounts of CH ablator material mixing into the hot spot [8,9], degrading the implosion performance. To increase the resistance to hydrodynamic instabilities [10], the "high-foot" drive design was developed [11,12], which has demonstrated an order-of-magnitude improvement in neutron yields with first evidence for additional heating from alpha particle stopping [13].…”

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confidence: 99%

Demonstration of High Performance in Layered Deuterium-Tritium Capsule Implosions in Uranium Hohlraums at the National Ignition Facility

Döppner¹,

Callahan²,

Hurricane³

et al. 2015

Phys. Rev. Lett.

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109

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We report on the first layered deuterium-tritium (DT) capsule implosions indirectly driven by a "highfoot" laser pulse that were fielded in depleted uranium hohlraums at the National Ignition Facility. Recently, high-foot implosions have demonstrated improved resistance to ablation-front Rayleigh-Taylor instability induced mixing of ablator material into the DT hot spot [Hurricane et al., Nature (London) 506, 343 (2014)]. Uranium hohlraums provide a higher albedo and thus an increased drive equivalent to an additional 25 TW laser power at the peak of the drive compared to standard gold hohlraums leading to higher implosion velocity. Additionally, we observe an improved hot-spot shape closer to round which indicates enhanced drive from the waist. In contrast to findings in the National Ignition Campaign, now all of our highest performing experiments have been done in uranium hohlraums and achieved total yields approaching 10 16 neutrons where more than 50% of the yield was due to additional heating of alpha particles stopping in the DT fuel. In indirect-drive inertial confinement fusion (ICF) [1,2], laser energy, converted to thermal x rays inside a high-Z cavity (hohlraum), ablatively drives the implosion of a spherical capsule containing a deuterium-tritium (DT) fuel layer. A high-velocity, low-entropy, highly symmetric implosion is required to form a hot spot of sufficiently high density and temperature from a combination of PdV work and alpha particle deposition. Above the ignition threshold, a self-sustained nuclear burn wave is launched igniting the surrounding compressed fuel layer. Ignition and burn is predicted for stagnation pressures above 300 Gbar [3].Experiments during the National Ignition Campaign (NIC) [4] demonstrated high implosion velocities (∼360 km=s) [5], and high areal mass densities of 1.3 AE 0.1 g=cm 2 [6], which were predicted to be sufficient to reach ignition [7]. However, some of them showed evidence for significant amounts of CH ablator material mixing into the hot spot [8,9], degrading the implosion performance. To increase the resistance to hydrodynamic instabilities [10], the "high-foot" drive design was developed [11,12], which has demonstrated an order-of-magnitude improvement in neutron yields with first evidence for additional heating from alpha particle stopping [13]. The high-foot drive raises the hohlraum temperature to 90 eV during the foot, launching a stronger first shock and sets the implosion on a higher adiabat. Among the benefits are a larger ablator density scale length (reducing susceptibility to ablation front RayleighTaylor growth [14]), and a shorter, simplified laser drive (three shocks rather than four). These benefits come at the price of lower fuel areal density, which requires higher implosion velocity compared to the low-entropy design [7] to achieve ignition.The first high-foot DT implosions [12,13,15] were done in gold (Au) hohlraums. These experiments incrementally increased laser peak power P laser and thus total laser energy from 351 TW=1.3 MJ on N13...

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“…In order to increase the significance of the measurements from SPIDER, the absolute characterization of the spectral sensitivity was executed at the High Energy X-ray (HEX) lab [7] at the National Security and Technologies, LLC (NSTec) Livermore facility. A determination of the absolute x-ray yield would be useful in several ways: (1) To gauge the relative quality of implosions or back-lighter strength among NIF experiments; (2) as an input parameter into a model that estimates the amount of material mixing that occurs from the capsule outer shell into the fuel layers of the DT capsule [8]; (3) If the x-ray yield is predicted for a particular experiment, then appropriate filtering can be chosen for SPIDER to optimize the dynamic range of the recorded signal. In addition, characterization was performed utilizing three different photocathodes: CsI with a thickness of 0.2 µm, 1.0 µm and 10 µm in order to determine which one is more efficient in the typical implosion energy range.…”

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confidence: 99%

Characterization of the x-ray sensitivity of a streak camera used at the National Ignition Facility (NIF)

et al. 2013

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A neutron hardened x-ray streak camera has been used to report x-ray burn duration and time of peak emission from imploding ICF capsules at the National Ignition Facility with  <30 ps. Recent characterization of the instrument using a NIST traceable High Energy X-ray reference source (HEX, National Security Technologies) will enable absolute capsule self-emission x-ray yield measurements (J/sr/keV). This manuscript describes the characterization procedure used and preliminary results of the x-ray sensitivity using three different thicknesses of the CsI photocathode.

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Onset of Hydrodynamic Mix in High-Velocity, Highly Compressed Inertial Confinement Fusion Implosions

Cited by 225 publications

References 36 publications

Comparison of two- and three-dimensional simulations of miscible Richtmyer-Meshkov instability with multimode initial conditions

Comparison of two- and three-dimensional simulations of miscible Richtmyer-Meshkov instability with multimode initial conditions

Demonstration of High Performance in Layered Deuterium-Tritium Capsule Implosions in Uranium Hohlraums at the National Ignition Facility

Characterization of the x-ray sensitivity of a streak camera used at the National Ignition Facility (NIF)

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