Capsule modeling of high foot implosion experiments on the National Ignition Facility

Clark, Dan; Kritcher, Andrea; Milovich, J. L.; Salmonson, J. D.; Weber, Christopher; Haan, S. W.; Hammel, B. A.; Hinkel, D. E.; Marinak, M. M.; Patel, Mehul V.; Sepke, S. M.

doi:10.1088/1361-6587/aa6216

Cited by 46 publications

(14 citation statements)

References 79 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While simulations suggest that the yield is degraded by 5-6Â in these implosions from a symmetric 1D implosion, the largest degradation source is predicted to be low-mode asymmetries, which degrade the yield by $15Â. 40 Thus removing the tent perturbation alone without improving other degradation sources should result in more modest performance improvements. These first two layered DT experiments used a 30 lm diameter fill-tube and a polar tent (as discussed in Fig.…”

Section: Performance Summarymentioning

confidence: 91%

“…The boot-strapping effect that can occur with a-deposition can produce significantly different yields based on subtle difference in simulation parameters, like resolution or how the a-particle slowing is modeled. 40 Therefore, no a-deposition calculations are a more faithful representation of the integrity of implosion. 24,41 and a large experimental dataset exists to compare with.…”

Section: Performance Summarymentioning

confidence: 99%

“…41,42 Table II shows that as the ablator is thinned, the effect of the tent increases in simulations. 40 Reducing the foot level to achieve a lower adiabat 43,44 (the so-called 3-shock or high foot adiabat shaping) is more sensitive to the tent than the high-foot at the same thickness. At a higher convergence, the low foot and adiabat shaped low foot 7 pulse shapes are the most sensitive to the tent.…”

Section: Performance Summarymentioning

confidence: 99%

See 2 more Smart Citations

Improving ICF implosion performance with alternative capsule supports

et al. 2017

View full text Add to dashboard Cite

The thin membrane that holds the capsule in-place in the hohlraum is recognized as one of the most significant contributors to reduced performance in indirect drive inertial confinement fusion (ICF) experiments on the National Ignition Facility. This membrane, known as the “tent,” seeds a perturbation that is amplified by Rayleigh-Taylor and can rupture the capsule. A less damaging capsule support mechanism is under development. Possible alternatives include the micron-scale rods spanning the hohlraum width and supporting either the capsule or stiffening the fill-tube, a larger fill-tube to both fill and support the capsule, or a low-density foam layer that protects the capsule from the tent impact. Experiments are testing these support features to measure their imprint on the capsule. These experiments are revealing unexpected aspects about perturbation development in indirect drive ICF, such as the importance of shadows coming from bright spots in the hohlraum. Two dimensional and 3D models are used to explain these features and assess the impact on implosion performance. Experiments and modeling suggest that the fill-tube supported by a perpendicular rod can mount the capsule without any additional perturbation beyond that of the fill tube.

show abstract

Section: Performance Summarymentioning

confidence: 91%

Section: Performance Summarymentioning

confidence: 99%

Section: Performance Summarymentioning

confidence: 99%

See 1 more Smart Citation

Improving ICF implosion performance with alternative capsule supports

et al. 2017

View full text Add to dashboard Cite

show abstract

“…The radiation drive is extracted from these lower-resolution integrated hohlraum and capsule simulations and imposed on higher-resolution capsule-only simulations 45,46 in two dimensions with symmetry along the axis (Extended Data Fig. 4), which can resolve a larger number of modes (≤200).…”

Section: Methodsmentioning

confidence: 99%

Design of inertial fusion implosions reaching the burning plasma regime

et al. 2022

View full text Add to dashboard Cite

In a burning plasma state1–7, alpha particles from deuterium–tritium fusion reactions redeposit their energy and are the dominant source of heating. This state has recently been achieved at the US National Ignition Facility8 using indirect-drive inertial-confinement fusion. Our experiments use a laser-generated radiation-filled cavity (a hohlraum) to spherically implode capsules containing deuterium and tritium fuel in a central hot spot where the fusion reactions occur. We have developed more efficient hohlraums to implode larger fusion targets compared with previous experiments9,10. This delivered more energy to the hot spot, whereas other parameters were optimized to maintain the high pressures required for inertial-confinement fusion. We also report improvements in implosion symmetry control by moving energy between the laser beams11–16 and designing advanced hohlraum geometry17 that allows for these larger implosions to be driven at the present laser energy and power capability of the National Ignition Facility. These design changes resulted in fusion powers of 1.5 petawatts, greater than the input power of the laser, and 170 kJ of fusion energy18,19. Radiation hydrodynamics simulations20,21 show energy deposition by alpha particles as the dominant term in the hot-spot energy balance, indicative of a burning plasma state.

show abstract

“…For this simulation, a surrogate tent scar perturbation is applied, derived from high fidelity capsule simulations that match convergent ablator (2DConA) data 38 . A surrogate is required as the tent membrane is 45nm in thickness, which is computationally intractable.…”

Section: B Tent Membranementioning

confidence: 99%

Diagnostic signatures of performance degrading perturbations in inertial confinement fusion implosions

et al. 2018

View full text Add to dashboard Cite

We present 3D radiation-hydrodynamics simulations of indirect-drive inertial confinement fusion experiments performed at the National Ignition Facility (NIF). The simulations are carried out on two shots from different NIF experimental campaigns: N130927 from the high foot series and N161023 from the ongoing high density carbon series. Applying representative perturbation sources from each implosion, synthetic nuclear diagnostics are used to post-process the simulations to infer the stagnation parameters. The underlying physical mechanisms that produce the observed signatures are then explored. We find that the radiation asymmetry and tent scar perturbations extend the nuclear burn width; this is due to an asymmetric stagnation of the shell that causes the delivery of mechanical PdV work to be extended compared to an idealised implosion. Radiation asymmetries seed directed flow patterns that can result in a difference in the inferred ion temperature ranging from 80 eV to 230 eV depending on the magnitude and orientation of the asymmetry considered in the simulation; the tent scar shows no such temperature difference. For N130927, radiation asymmetries dominate the yield and inferred ion temperature and the tent scar has the largest influence on the neutron burnwidth. For N161023, the fill tube decreases the burn width by injecting mix into the hot spot, leading to a smaller hot spot and increased energy losses. Both the radiation asymmetry and the fill tube generate directed flows that lead to an anisotropic inferred temperature distribution. Through existing and novel synthetic neutron imaging techniques, we can observe the hot spot and shell shape to a degree that accurately captures the perturbations present.

show abstract

Capsule modeling of high foot implosion experiments on the National Ignition Facility

Cited by 46 publications

References 79 publications

Improving ICF implosion performance with alternative capsule supports

Improving ICF implosion performance with alternative capsule supports

Design of inertial fusion implosions reaching the burning plasma regime

Diagnostic signatures of performance degrading perturbations in inertial confinement fusion implosions

Contact Info

Product

Resources

About