A high-resolution integrated model of the National Ignition Campaign cryogenic layered experiments

Jones, O. S.; Cerjan, C.; Marinak, M. M.; Milovich, J. L.; Robey, H. F.; Springer, P. T.; Benedetti, L. R.; Bleuel, D. L.; Bond, E.; Bradley, D. K.; Callahan, D. A.; Caggiano, J. A.; Celliers, P. M.; Clark, Dan; Dixit, S.; Döppner, T.; Dylla‐Spears, Rebecca; Dzentitis, E. G.; Farley, D. R.; Glenn, S.; Glenzer, S. H.; Haan, S. W.; Haid, B. J.; Haynam, Christopher A.; Hicks, D. G.; Kozioziemski, B.; LaFortune, K. N.; Landen, O. L.; Mapoles, E. R.; Mackinnon, A. J.; McNaney, J. M.; Meezan, N. B.; Michel, P.; Moody, J. D.; Moran, M. J.; Munro, D. H.; Patel, Mehul V.; Parham, T.; Sater, J.; Sepke, S. M.; Spears, B. K.; Town, R. P. J.; Weber, S. V.; Widmann, K.; Widmayer, C.; Williams, E. A.; Atherton, L. J.; Edwards, M. J.; Lindl, J. D.; MacGowan, B. J.; Suter, L. J.; Olson, R. E.; Herrmann, H. W.; Kline, J. L.; Kyrala, G. A.; Wilson, D. C.; Frenje, J. A.; Boehly, T. R.; Glebov, V. Yu.; Knauer, J. P.; Nikroo, A.; Wilkens, H. L.; Kilkenny, J. D.

doi:10.1063/1.4718595

Cited by 114 publications

(30 citation statements)

References 14 publications

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“…In inertial confinement fusion (ICF) experiments, 6,7 this distribution is usually measured 8 in the neutron time-of-flight domain using scintillation detectors operated in current mode 9 or neutron detector arrays, 10 but has also been measured using proton or other charged-particle recoil methods. 11 Neutron spectral widths from ICF experiments have often been observed to be wider than expected from simulations [12][13][14] or the measured yield. 15 This has been attributed to mass flows within the reacting region, 15,16 higher contributions to the spatially averaged ion temperature from the hottest central regions of the core, 12 and expansion of the reacting plasma at velocities near the sound speed.…”

Section: Introductionmentioning

confidence: 94%

The effect of turbulent kinetic energy on inferred ion temperature from neutron spectra

Murphy

2014

Physics of Plasmas

112

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Measuring the width of the energy spectrum of fusion-produced neutrons from deuterium (DD) or deuterium-tritium (DT) plasmas is a commonly used method for determining the ion temperature in inertial confinement fusion (ICF) implosions. In a plasma with a Maxwellian distribution of ion energies, the spread in neutron energy arises from the thermal spread in the center-of-mass velocities of reacting pairs of ions. Fluid velocities in ICF are of a similar magnitude as the center-of-mass velocities and can lead to further broadening of the neutron spectrum, leading to erroneous inference of ion temperature. Motion of the reacting plasma will affect DD and DT neutrons differently, leading to disagreement between ion temperatures inferred from the two reactions. This effect may be a contributor to observations over the past decades of ion temperatures higher than expected from simulations, ion temperatures in disagreement with observed yields, and different temperatures measured in the same implosion from DD and DT neutrons. This difference in broadening of DD and DT neutrons also provides a measure of turbulent motion in a fusion plasma.

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Section: Introductionmentioning

confidence: 94%

The effect of turbulent kinetic energy on inferred ion temperature from neutron spectra

Murphy

2014

Physics of Plasmas

112

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“…In particular, current CH capsule simulations employ the $0:85 main pulse multiplier. 21 The power multiplier of 1.0 was used for Revs. 3 and 3.1 NIF Be target design.…”

Section: Introductionmentioning

confidence: 99%

Optimized beryllium target design for indirectly driven inertial confinement fusion experiments on the National Ignition Facility

Simakov

Wilson

et al. 2014

Physics of Plasmas

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For indirect drive inertial confinement fusion, Beryllium (Be) ablators offer a number of important advantages as compared with other ablator materials, e.g., plastic and high density carbon. In particular, the low opacity and relatively high density of Be lead to higher rocket efficiencies giving a higher fuel implosion velocity for a given X-ray drive; and to higher ablation velocities providing more ablative stabilization and reducing the effect of hydrodynamic instabilities on the implosion performance. Be ablator advantages provide a larger target design optimization space and can significantly improve the National Ignition Facility (NIF) [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)] ignition margin. Herein, we summarize the Be advantages, briefly review NIF Be target history, and present a modern, optimized, low adiabat, Revision 6 NIF Be target design. This design takes advantage of knowledge gained from recent NIF experiments, including more realistic levels of laser-plasma energy backscatter, degraded hohlraum-capsule coupling, and the presence of cross-beam energy transfer. V C 2014 AIP Publishing LLC. [http://dx.

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“…19 The only adjustment to drive used for simulations to match time of peak neutron emission is that peak power is reduced by 10%; this reduction appears to compensate for uncertainties in the HDC equation of state and gold atomic physics modeling. The agreement between experimental and simulated parameters has been verified through several experiments using a suite of tuning targets, including shock timing (keyhole) targets, 25 hydrogrowth radiography (HGR) targets, 26 and backlit radiography convergent ablator targets.…”

Section: Dynamic Beam Phasingmentioning

confidence: 99%

Near-vacuum hohlraums for driving fusion implosions with high density carbon ablatorsa)

et al. 2015

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Recent experiments at the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] have explored driving high-density carbon ablators with near-vacuum hohlraums, which use a minimal amount of helium gas fill. These hohlraums show improved efficiency relative to conventional gas-filled hohlraums in terms of minimal backscatter, minimal generation of suprathermal electrons, and increased hohlraum-capsule coupling. Given these advantages, near-vacuum hohlraums are a promising choice for pursuing high neutron yield implosions. Long pulse symmetry control, though, remains a challenge, as the hohlraum volume fills with material. Two mitigation methodologies have been explored, dynamic beam phasing and increased case-to-capsule ratio (larger hohlraum size relative to capsule). Unexpectedly, experiments have demonstrated that the inner laser beam propagation is better than predicted by nominal simulations, and an enhanced beam propagation model is required to match measured hot spot symmetry. Ongoing work is focused on developing a physical model which captures this enhanced propagation and on utilizing the enhanced propagation to drive longer laser pulses than originally predicted in order to reach alpha-heating dominated neutron yields. V C 2015 AIP Publishing LLC. INTRODUCTIONAchieving ignition-where the energy output from inertial confinement fusion (ICF) reactions is higher than the energy input to drive the reaction-requires reaching sufficiently high implosion densities and temperatures. Proximity of the implosion to ignition conditions can be characterized through the Ignition Threshold Factor (ITF) 1-3 ITF / v 8 a À4 1 À 1:2 DR R hotspot 4 M clean M DT 0:5 ;(1)where v denotes the implosion velocity; a is the adiabat at peak velocity; the third term captures degradation due to deviation (DR) from spherical symmetry (where R is the 1D hotspot radius); 4,5 M clean is the mass of fuel without ablator mix; and M DT is the initial mass of deuterium-tritium fuel. As denoted through Eq. (1), reaching ignition has a strong dependence on implosion velocity, which highlights the need for a highly efficient hohlraum to drive the implosion in indirectdrive ICF. 6 In this paper, we describe recent efforts at the National Ignition Facility (NIF) 7,8 to develop a more efficient hohlraum with progressively reduced adiabat implosions as well as associated methodologies for symmetry control. The NIF is composed of 192 laser beams that, after frequency tripling to 351 nm, are incident on the two endcaps (laser entrance holes or LEHs) of a gold, cylindrical hohlraum. Half of the beams enter each LEH and propagate to the hohlraum wall where conversion to x-ray radiation occurs. This radiation then ablates and implodes a deuterium-tritium (DT) fuel-filled capsule. On the NIF, the laser beams are grouped into "inner" and "outer" beams, which are pointed to provide x-ray drive to the waist and pole, respectively, of the imploding capsule.Low-Z gas-filled hohlraums are typically utilized due to the pulse length...

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A high-resolution integrated model of the National Ignition Campaign cryogenic layered experiments

Cited by 114 publications

References 14 publications

The effect of turbulent kinetic energy on inferred ion temperature from neutron spectra

The effect of turbulent kinetic energy on inferred ion temperature from neutron spectra

Optimized beryllium target design for indirectly driven inertial confinement fusion experiments on the National Ignition Facility

Near-vacuum hohlraums for driving fusion implosions with high density carbon ablatorsa)

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