Direct-drive laser target designs for sub-megajoule energies

Colombant, D.; Schmitt, A. J.; Obenschain, S. P.; Zalesak, S. T.; Velikovich, A. L.; Bates, Jason W.; Fyfe, David; Gardner, John; Manheimer, Wallace M.

doi:10.1063/1.2730503

Cited by 11 publications

(4 citation statements)

References 21 publications

(24 reference statements)

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“…Details of the ongoing development of sub-MJ implosion designs with KrF lasers are discussed in another paper. 7 Application of high intensity laser pulses to direct and indirect drive implosions is limited by the occurrence of LPI in the underdense plasma surrounding the pellet. 9 Deep ultraviolet (248 nm) KrF lasers will help mitigate the risk from LPI.…”

Section: Introductionmentioning

confidence: 99%

Laser plasma instability experiments with KrF lasers

Weaver

Afeyan

et al. 2007

Physics of Plasmas

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Deleterious effects of laser-plasma instability (LPI) may limit the maximum laser irradiation that can be used for inertial confinement fusion. The short wavelength (248 nm), large bandwidth, and very uniform illumination available with krypton-fluoride (KrF) lasers should increase the maximum usable intensity by suppressing LPI. The concomitant increase in ablation pressure would allow implosion of low aspect ratio pellets to ignition with substantial gain (>20) at much reduced laser energy. The proposed KrF laser based Fusion Test Facility (FTF) would exploit this strategy to achieve significant fusion power (150 MW) with a rep-rate system that has a per pulse laser energy well below 1 megajoule.

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Section: Introductionmentioning

confidence: 99%

Laser plasma instability experiments with KrF lasers

Weaver

Afeyan

et al. 2007

Physics of Plasmas

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“…The facility design incorporated and extended the HAPL database but required a target design energy scaled down from the original 2.5 MJ to the anticipated 500-kJ KrF laser. Colombant et al 871 accomplished this, predicting 1-D target gains of just over 50. Other attractive features of the FTF include the implementation and testing of 5-Hz implosion operation and the application of functional focal-spot zooming. In support of the proposed FTF, Kehne et al 872 at NRL demonstrated focal-spot zooming by a margin (4.5:1) that exceeds what would be required by the FTF.…”

Section: Ignition and High-gain Target Designsmentioning

confidence: 97%

Direct-drive inertial confinement fusion: A review

et al. 2015

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The direct-drive, laser-based approach to inertial confinement fusion (ICF) is reviewed from its inception following the demonstration of the first laser to its implementation on the present generation of high-power lasers. The review focuses on the evolution of scientific understanding gained from target-physics experiments in many areas, identifying problems that were demonstrated and the solutions implemented. The review starts with the basic understanding of laser–plasma interactions that was obtained before the declassification of laser-induced compression in the early 1970s and continues with the compression experiments using infrared lasers in the late 1970s that produced thermonuclear neutrons. The problem of suprathermal electrons and the target preheat that they caused, associated with the infrared laser wavelength, led to lasers being built after 1980 to operate at shorter wavelengths, especially 0.35 μm—the third harmonic of the Nd:glass laser—and 0.248 μm (the KrF gas laser). The main physics areas relevant to direct drive are reviewed. The primary absorption mechanism at short wavelengths is classical inverse bremsstrahlung. Nonuniformities imprinted on the target by laser irradiation have been addressed by the development of a number of beam-smoothing techniques and imprint-mitigation strategies. The effects of hydrodynamic instabilities are mitigated by a combination of imprint reduction and target designs that minimize the instability growth rates. Several coronal plasma physics processes are reviewed. The two-plasmon–decay instability, stimulated Brillouin scattering (together with cross-beam energy transfer), and (possibly) stimulated Raman scattering are identified as potential concerns, placing constraints on the laser intensities used in target designs, while other processes (self-focusing and filamentation, the parametric decay instability, and magnetic fields), once considered important, are now of lesser concern for mainline direct-drive target concepts. Filamentation is largely suppressed by beam smoothing. Thermal transport modeling, important to the interpretation of experiments and to target design, has been found to be nonlocal in nature. Advances in shock timing and equation-of-state measurements relevant to direct-drive ICF are reported. Room-temperature implosions have provided an increased understanding of the importance of stability and uniformity. The evolution of cryogenic implosion capabilities, leading to an extensive series carried out on the 60-beam OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)], is reviewed together with major advances in cryogenic target formation. A polar-drive concept has been developed that will enable direct-drive–ignition experiments to be performed on the National Ignition Facility [Haynam et al., Appl. Opt. 46(16), 3276 (2007)]. The advantages offered by the alternative approaches of fast ignition and shock ignition and the issues associated with these concepts are described. The lessons learned from target-physics and implosion experiments are taken into account in ignition and high-gain target designs for laser wavelengths of 1/3 μm and 1/4 μm. Substantial advances in direct-drive inertial fusion reactor concepts are reviewed. Overall, the progress in scientific understanding over the past five decades has been enormous, to the point that inertial fusion energy using direct drive shows significant promise as a future environmentally attractive energy source.

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“…13 is NRL's original calculation [65] of what is called central ignition. The same laser pulse is used to both compress the inner part of the target and to heat it.…”

Section: Direct Drivementioning

confidence: 99%

Fusion Breeding for Mid-Century Sustainable Power

Manheimer

2014

J Fusion Energ

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This article is an editorial, which makes the case that fusion breeding (that is using fusion neutrons to breed nuclear fuel for use in conventional nuclear reactors) is the best objective for the fusion program. To make the case, it reviews a great deal of plasma physics and fusion data. Fusion breeding could potentially play a key role in delivering large-scale sustainable carbon-free commercial power by mid-century. There is almost no chance that pure fusion can do that. The leading magnetic fusion concept, the tokamak, is subject to well-known constraints, which we have called conservative design rules, and review in this paper. These constraints will very likely prevent tokamaks from ever delivering economical pure fusion. Inertial fusion, in pure fusion mode, may ultimately be able to deliver commercial power, but the failure to date of the leading inertial fusion experiment, the National Ignition Campaign, shows that there are still large gaps in our understanding of laser fusion. Fusion breeding, based on either magnetic fusion or inertial fusion, greatly relaxes the requirements on the fusion reactor. It is also a much better fit to today's and tomorrow's nuclear infrastructure than is its competitor, fission breeding. This article also shows that the proposed fusion and fission infrastructure, 'The Energy Park', reviewed here, is sustainable, economically and environmentally sound, and poses little or no proliferation risk.

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Direct-drive laser target designs for sub-megajoule energies

Cited by 11 publications

References 21 publications

Laser plasma instability experiments with KrF lasers

Laser plasma instability experiments with KrF lasers

Direct-drive inertial confinement fusion: A review

Fusion Breeding for Mid-Century Sustainable Power

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