Prospects for high-gain, high yield National Ignition Facility targets driven by 2ω (green) light

Suter, L. J.; Glenzer, S. H.; Haan, S. W.; Hammel, B. A.; Manes, Kenneth R.; Meezan, N. B.; Moody, J. D.; Spaeth, M. L.; Divol, L.; Oades, K.; Stevenson, M.

doi:10.1063/1.1687725

Cited by 30 publications

(23 citation statements)

References 21 publications

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“…Thus, post ignition pressures and temperatures are very different from pre-ignition numbers. Larger ICF capsules that are designed for high-gain fusion experiments [79,80] use about an order of magnitude more fuel, but overall the P τ conditions are not be very different.…”

Section: Pressurementioning

confidence: 99%

Cryogenic thermonuclear fuel implosions on the National Ignition Facility

et al. 2012

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The first inertial confinement fusion implosion experiments with equimolar deuterium-tritium thermonuclear fuel have been performed on the National Ignition Facility. These experiments use 0.17 mg of fuel with the potential for ignition and significant fusion yield conditions. The thermonuclear fuel has been fielded as a cryogenic layer on the inside of a spherical plastic capsule that is mounted in the center of a cylindrical gold hohlraum. Heating the hohlraum with 192 laser beams for a total laser energy of 1.6 mega joules produces a soft x-ray field with 300 eV temperature. The ablation pressure produced by the radiation field compresses the initially 2.2-mm diameter capsule by a factor of 30 to a spherical dense fuel shell that surrounds a central hot-spot plasma of 50 µm diameter. While an extensive set of x-ray and neutron diagnostics has been applied to characterize hot spot formation from the x-ray emission and 14.1 MeV deuterium-tritium primary fusion neutrons, thermonuclear fuel assembly is studied by measuring the down-scattered neutrons with energies in the range of 10 to 12 MeV. X-ray and neutron imaging of the compressed core and fuel indicate a fuel thickness of (14 ± 3) µm, which combined with magnetic recoil spectrometer measurements of the fuel areal density of (1 ± 0.09) g cm −2 result in fuel densities approaching 600 g cm −3 . The fuel surrounds a hot-spot plasma with average ion temperatures of (3.5 ± 0.1) keV that is measured with neutron time of flight spectra. Absolute neutron yields of (7.5 ± 0.1) × 10 14 have been recorded from the magnetic recoil spectrometer and nuclear activation diagnostics while gamma ray measurements provide the duration of nuclear activity of (170 ± 30) ps. These indirect-drive implosions result in the highest areal densities and neutron yields achieved on laser facilities to date. This achievement is the result of the first hohlraum and capsule tuning experiments where the stagnation pressures have been systematically increased by more than a factor of 10 by fielding low-entropy implosions through the control of radiation symmetry, small hot electron production, and proper shock timing. The stagnation pressure is above 100 Gbar resulting in high Lawson confinement parameters of P τ 10 atm s. Comparisons with radiation-hydrodynamic simulations indicate that the pressure is within a factor of three required for reaching ignition and high yield. This will be the focus of future higher-velocity implosions that will employ additional optimizations of hohlraum, capsule and laser pulse shape conditions.

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Section: Pressurementioning

confidence: 99%

Cryogenic thermonuclear fuel implosions on the National Ignition Facility

et al. 2012

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“…The two issues greatly limit the maximum energy output capability of a 3ω laser facility. In contrast, 2ω laser can highly increase the threshold for optical damages, which therefore results in a lower operation costs for a laser facility and a higher laser energy deliverable on target [11,12]. Furthermore, in the long term, any reactor based on laser-driven ICF will require laser operation at sufficiently high wavelength for keeping the live time of the optics at a level that meets the energy production requirements [13].…”

Section: Introductionmentioning

confidence: 99%

Foam Au driven by 4ω–2ω ignition laser pulse for inertial confinement fusion

Lan

Song

2017

Physics of Plasmas

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Green light (2ω) has the potential to drive ignition target for laser fusion with significantly more energy than blue light (3ω) and a relatively higher damage threshold for the optic components in the final optic assembly, but it has issues of a relatively low laser to x-ray conversion efficiency and a hard x-ray spectrum as compared to 3ω. In this paper, we propose to drive a foam hohlraum wall with an ignition laser pulse by taking a 4ω laser at the pre-pulse and a 2ω laser at the main-pulse, called as 4ω -2ω ignition pulse. This novel design has the following advantages: (1) benefiting from 2ω of its relatively high energy output and low damage threshold during main-pulse; (2) benefiting from foam in its relatively high laser to x-ray conversion efficiency and relatively low M-band fraction in re-emission; (3) benefiting from 4ω of its low LPI during pre-pulse. From our 1D simulations with Au material, the laser to x-ray conversion in a foam driven by 4ω -2ω pulse has an increase of 28% as compared to a solid target driven by 3ω with the same pulse shape. The relatively thin optical depth of foam is one of the main reasons for the increase of laser to x-ray conversion efficiency inside a foam target.

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“…34 It may also be possible to study thermonuclear reactions in highly screened, dense plasmas, relevant to reactions in dwarf stars. Finally, if high gain ͑G Ͼ 100͒ implosions can be produced, 35 it may be possible to examine some of the physics issues surrounding the proposed deflagration-to-detonation transition, and the role of hydrodynamic mixing, relevant to type la supermovas. 36 …”

Section: A Burning Plasmasmentioning

confidence: 99%

The National Ignition Facility: Ushering in a new age for high energy density science

Moses¹,

Boyd²,

Remington³

et al. 2009

Physics of Plasmas

419

221

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The National Ignition Facility (NIF) [E. I. Moses, J. Phys.: Conf. Ser. 112, 012003 (2008); https://lasers.llnl.gov/], completed in March 2009, is the highest energy laser ever constructed. The high temperatures and densities achievable at NIF will enable a number of experiments in inertial confinement fusion and stockpile stewardship, as well as access to new regimes in a variety of experiments relevant to x-ray astronomy, laser-plasma interactions, hydrodynamic instabilities, nuclear astrophysics, and planetary science. The experiments will impact research on black holes and other accreting objects, the understanding of stellar evolution and explosions, nuclear reactions in dense plasmas relevant to stellar nucleosynthesis, properties of warm dense matter in planetary interiors, molecular cloud dynamics and star formation, and fusion energy generation.

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Prospects for high-gain, high yield National Ignition Facility targets driven by 2ω (green) light

Cited by 30 publications

References 21 publications

Cryogenic thermonuclear fuel implosions on the National Ignition Facility

Cryogenic thermonuclear fuel implosions on the National Ignition Facility

Foam Au driven by 4ω–2ω ignition laser pulse for inertial confinement fusion

The National Ignition Facility: Ushering in a new age for high energy density science

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