Inertial Confinement Fusion with Tetrahedral Hohlraums at OMEGA

Wallace, Jessica; Murphy, T. J.; Delamater, N. D.; Klare, K. A.; Oertel, J. A.; Magelssen, G. R.; Lindman, E. L.; Hauer, A.; Gobby, P. L.; Schnittman, Jeremy D.; Craxton, R. S.; Seka, W.; Kremens, R. L.; Bradley, D. K.; Pollaine, S. M.; Turner, R. E.; Landen, O. L.; Drake, D. M.; Macfarlane, J. J.

doi:10.1103/physrevlett.82.3807

Cited by 41 publications

(28 citation statements)

References 21 publications

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“…r 12 is the distance between differential surface area elements 1 and 2) assessment (e.g., [17]). Thus, some improvement in hohlraum smoothing of radiation asymmetry between the wall and outer shell is expected with a rugby hohlraum compared with a cylinder of the same surface area.…”

Section: High-gain Double-shell Design With Vacuum Hohlraumsmentioning

confidence: 99%

Assessing the prospects for achieving double-shell ignition on the National Ignition Facility using vacuum hohlraums

et al. 2007

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The goal of demonstrating ignition on the National Ignition Facility (NIF) has motivated a revisit of double-shell (DS) targets as a complementary path to the cryogenic baseline approach. Expected benefits of DS ignition targets include non-cryogenic deuterium-tritium (DT) fuel preparation, minimal hohlraum-plasma mediated laser backscatter, low thresholdignition temperatures (≈ 4 keV) for relaxed hohlraum x-ray flux asymmetry tolerances, and minimal (two-) shock timing requirements. On the other hand, DS ignition presents several formidable challenges, encompassing room-temperature containment of high-pressure DT (≈ 790 atm) in the inner shell, strict concentricity requirements on the two shells (< 3 µm), development of nano-porous (<100 nm) low-density (<100 mg/cc) metallic foams for structural support of the inner shell and hydrodynamic instability mitigation, and effective control of hydrodynamic instabilities on the high-Atwood number interface between the DT fuel and the high-Z inner shell. Recent progress in DS ignition designs and required materials-science advances at the nanoscale are described herein. Two new ignition designs that use rugby-shaped vacuum hohlraums are presented which utilize either 1 MJ or 2 MJ of laser energy at 3ω. The capability of the NIF to generate the requested reverse-ramp pulse shape for DS ignition is expected to be comparable to the planned high-contrast (≈100) pulse-shape at 1.8 MJ for the baseline cryogenic target. Nano-crystalline, high-strength, AuCu alloy inner shells are under development using electrochemical deposition over a glass mandrel, exhibiting tensile strengths well in excess of 790 atm. Novel, low-density (85 mg/cc) copper foams have recently been demonstrated using 10 mg/cc SiO 2 nano-porous aerogels with suspended Cu particles. A prototype demonstration of an ignition DS is planned for 2008, incorporating the needed novel nano-materials science developments and the required fabrication tolerances for a realistic ignition attempt after 2010.

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Section: High-gain Double-shell Design With Vacuum Hohlraumsmentioning

confidence: 99%

Assessing the prospects for achieving double-shell ignition on the National Ignition Facility using vacuum hohlraums

et al. 2007

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“…However, a high symmetry on capsule inside the cylindrical hohlraums is realized by tuning via beam-phasing technology and three-color technology, while the tuning experiments have shown that none of layered implosions to date meet the symmetry requirement for ignition [4e7]. In fact, many experimental and theoretical works have shown that the octahedral spherical hohlraums with 6 LEHs [8e10] and the tetrahedral spherical hohlraums with 4 LEHs [11,12] have natural superiority over the cylindrical hohlraums in maintaining high radiation symmetry during the whole capsule implosion process and are much more insensitive to the random variations [13]. As a result, the spherical hohlraum is a hopeful candidate for ignition hohlraum.…”

mentioning

confidence: 99%

First demonstration of improving laser propagation inside the spherical hohlraums by using the cylindrical laser entrance hole

Huo

Yang

et al. 2016

Matter and Radiation at Extremes

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The octahedral spherical hohlraums have natural superiority in maintaining high radiation symmetry during the entire capsule implosion process in indirect drive inertial confinement fusion. While, in contrast to the cylindrical hohlraums, the narrow space between the laser beams and the spherical hohlraum wall is usually commented. In this Letter, we address this crucial issue and report our experimental work conducted on the SGIII-prototype laser facility which unambiguously demonstrates that a simple design of cylindrical laser entrance hole (LEH) can dramatically improve the laser propagation inside the spherical hohlraums. In addition, the laser beam deflection in the hohlraum is observed for the first time in the experiments. Our 2-dimensional simulation results also verify qualitatively the advantages of the spherical hohlraums with cylindrical LEHs. Our results imply the prospect of adopting the cylindrical LEHs in future spherical ignition hohlraum design.

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“…The concept of tetrahedral hohlraum was first proposed by Phillion and Pollaine, 12 and the first experiment with this kind of hohlraum was done at OMEGA by Wallace et al 13 In that experiment, the tetrahedral hohlraums of R H /R C ¼ 2.56-4 were used, with multi laser cones entering from each LEH. Here, we consider a tetrahedral hohlraum with only one cone of six quad beams from each LEH, and take R C ¼ 1.13 mm, R L ¼ 1 mm, R Q ¼ 0.3 mm, and h L ¼ 55 in our model.…”

Section: Octahedral Hohlraummentioning

confidence: 99%

Octahedral spherical hohlraum and its laser arrangement for inertial fusion

Lan

Liu

et al. 2014

Physics of Plasmas

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A recent publication [K. Lan et al., Phys. Plasmas 21, 010704 (2014)] proposed a spherical hohlraum with six laser entrance holes of octahedral symmetry at a specific hohlraum-to-capsule radius ratio of 5.14 for inertial fusion study, which has robust high symmetry during the capsule implosion and superiority on low backscatter without supplementary technology. This paper extends the previous one by studying the laser arrangement and constraints of octahedral hohlraum in detail. As a result, it has serious beam crossing at h L 45 , and h L ¼ 50 to 60 is proposed as the optimum candidate range for the golden octahedral hohlraum, here h L is the opening angle that the laser quad beam makes with the Laser Entrance Hole (LEH) normal direction. In addition, the design of the LEH azimuthal angle should avoid laser spot overlapping on hohlraum wall and laser beam transferring outside hohlraum from a neighbor LEH. The octahedral hohlraums are flexible and can be applicable to diverse inertial fusion drive approaches. This paper also applies the octahedral hohlraum to the recent proposed hybrid indirect-direct drive approach. V C 2014 AIP Publishing LLC.

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Inertial Confinement Fusion with Tetrahedral Hohlraums at OMEGA

Cited by 41 publications

References 21 publications

Assessing the prospects for achieving double-shell ignition on the National Ignition Facility using vacuum hohlraums

Assessing the prospects for achieving double-shell ignition on the National Ignition Facility using vacuum hohlraums

First demonstration of improving laser propagation inside the spherical hohlraums by using the cylindrical laser entrance hole

Octahedral spherical hohlraum and its laser arrangement for inertial fusion

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