Beryllium capsule implosions at a case-to-capsule ratio of 3.7 on the National Ignition Facility

Zylstra, A. B.; Yi, Sunghwan; MacLaren, S. A.; Kline, J. L.; Kyrala, G. A.; Ralph, J. E.; Bae, J. H.; Batha, S. H.; Callahan, D. A.; Flippo, K. A.; Huang, H.; Hurricane, O. A.; Khan, S. F.; Kabadi, N.; Kong, C.; Kot, L.; Lahmann, B.; Loomis, Eric; Massé, L.; Millot, Marius; Moore, A. S.; Nikroo, A.; Perry, T. S.; Rice, N.; Salmonson, J. D.; Shah, Rahul; Sio, H.; Stadermann, Michael; Strozzi, D. J.; Tipton, Robert; Xu, Hongwei

doi:10.1063/1.5041285

Cited by 25 publications

(10 citation statements)

References 52 publications

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“…We note that the inclusion of other, realistic sources of perturbation, such as the fill-tube might affect the ignition scaling. In addition, other capsule and hohlraum designs currently being explored on NIF (such as Bigfoot [12], Beryllium [39], HybridB) may be more robust to perturbations than the N161023-based design explored here. Our investigation indicates that this specific design can indeed reach energy yields of 1MJ, even in the presence of large-amplitude perturbations.…”

Section: Discussionmentioning

confidence: 98%

Burn regimes in the hydrodynamic scaling of perturbed inertial confinement fusion hotspots

Tong¹,

McGlinchey²,

Appelbe³

et al. 2019

Nucl. Fusion

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We present simulations of ignition and burn based on the Highfoot and High-Density Carbon indirect drive designs of the National Ignition Facility for three regimes of alpha-heating -self-heating, robust ignition and propagating burn -exploring hotspot power balance, perturbations and hydrodynamic scaling. A Monte-Carlo Particle-in-Cell charged particle transport package for the radiation-magnetohydrodynamics code Chimera was developed for this purpose, using a linked-list type data structure.The hotspot power balance between alpha-heating, electron thermal conduction and radiation was investigated in 1D for the three burn regimes. The impact of perturbations on this power balance is explored in 3D using a single Rayleigh-Taylor spike. Heat flow into the perturbation from thermal conduction and alpha-heating increases by factors of ∼2 − 3, due to sharper temperature gradients and increased proximity of the cold, dense material to the main fusion regions respectively. The radiative contribution remains largely unaffected in magnitude.Hydrodynamic scaling with capsule size and laser energy of different perturbation scenarios (a short-wavelength multi-mode and a low-mode radiation asymmetry) is explored in 3D, demonstrating the differing hydrodynamic evolution of the three alpha-heating regimes. The multi-mode yield increases faster with scale factor due to more synchronous P dV compression producing higher temperatures and densities, and therefore stronger bootstrapping of alphaheating. Effects on the hydrodynamic evolution are more prominent for stronger alpha-heating regimes, and include: reduced perturbation growth due to ablation from both fire-polishing and stronger thermal conduction; sharper temperature and density gradients at the boundary; and increased hotspot pressures which further compress the shell, increase hotspot size and induce faster re-expansion. The faster expansion into regions of weak confinement is more prominent for stronger alpha-heating regimes, and can result in loss of confinement.

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Section: Discussionmentioning

confidence: 98%

Burn regimes in the hydrodynamic scaling of perturbed inertial confinement fusion hotspots

Tong¹,

McGlinchey²,

Appelbe³

et al. 2019

Nucl. Fusion

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“…Additionally, the efficiency of the energy conversion from the laser into the X-ray field would be further reduced. Although this effect could be mitigated by using larger hohlraums, the total laser energy available with the current facilities limits the ratio between the radius of the hohlraum and that of the capsule, or case-to-capsule ratio (CCR), to values of 3 − 4 [10,15,16], which is not enough to avoid the gold plasma getting in the way of the laser beams.…”

Section: Indirect Drive Icfmentioning

confidence: 99%

Spectroscopic characterisation of the effects of plasma geometry on the angular distribution of X-Ray emission in HED plasmas

Perez-Callejo¹

2020

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The author gratefully acknowledges support from Lawrence Livermore National Laboratory under grant number B617350. The author wants to thank the experimental crew of the Omega laser at the University of Rochester Laboratory for Laser Energetics for expertly executing the experiments described here. The targets for those experiments were fabricated by General Atomics thanks to support from the National Nuclear Security Administration under contract DE-NA0001808.

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“…3 Increasing the CCR is known to improve the symmetry of the implosion, but CCR much larger than three was thought to be unnecessary and would decrease the drive on the capsule [1]. Concurrent experiments using beryllium capsules showed a larger CCR did provide greater symmetry [96]. In addition, the beam cone power fraction 4 during the foot pulse was varied until the shocks at the pole and equator of the capsule were simultaneous.…”

Section: The 2-shock Platformmentioning

confidence: 99%

“…Only two different metals have been used for ICF implosions: beryllium and aluminum. While beryllium capsules have been considered for many years as a leading candidate for indirect-drive ignition [122,123], few experiments using Be capsules have been performed [96,124]. Indirect-drive experiments using aluminum outer shells are now fielded routinely at NIF for double-shell highyield concepts [125][126][127].…”

Section: 2 Metal Capsulesmentioning

confidence: 99%

Effect of Impurity Atoms on Thermonuclear Yield

Batha

2020

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The presence of impurity atoms in an inertial confinement fusion (ICF) implosion can greatly affect the burning of the thermonuclear fuel. This is a serious concern for attaining ignition as high atomic number atoms, such as carbon, can mix into the hot spot and reach the deuterium-tritium (DT) fuel, absorb energy from the implosion, and radiate away that energy. The temperature of the DT fuel drops and reduces the reactivity of the fuel resulting in lower thermonuclear yield. Fuel impurities can also be a useful diagnostic as when higher-Z atoms, such as Ar, Kr, and Xe, are purposefully mixed into the fuel. From the spectra emitted by these atoms, the temperature and density of the fuel can be deduced. The long history of using such tracer atoms by the national ICF program shows the great advances in experimental technique, diagnostic instruments, and atomic-physics modeling over the past 50 years. A particular set of experiments, the "High-Z" campaign, is reviewed in depth as this was the most systematic study of tracer element composition and quantity ever reported. Difficulties in interpreting the results of those experiments due to the limited code capabilities at that time are discussed. A main concern for the High-Z campaign was the then current state of non-Local Thermodynamic Equilibrium (nLTE) atomic physics models. The present state of nLTE modeling and its implementation in Los Alamos's multi-physics codes is discussed in this report. To further the understanding of the complex interaction of high-Z atoms in the gas, a survey of relevant existing experimental platforms at the National Ignition Facility (NIF) and the Omega Laser Facility are presented along with the current state of pertinent diagnostics at NIF and Omega. This review concludes with a discussion of the trade-off available between temperature and volume of the imploded ICF capsule with the goal of maximizing the total yield. 10 24 cm•3 3 x 10 23 cm•3

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Beryllium capsule implosions at a case-to-capsule ratio of 3.7 on the National Ignition Facility

Cited by 25 publications

References 52 publications

Burn regimes in the hydrodynamic scaling of perturbed inertial confinement fusion hotspots

Burn regimes in the hydrodynamic scaling of perturbed inertial confinement fusion hotspots

Spectroscopic characterisation of the effects of plasma geometry on the angular distribution of X-Ray emission in HED plasmas

Effect of Impurity Atoms on Thermonuclear Yield

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