Direct drive double shell target implosion hydrodynamics on 
OMEGA

Kyrala, G. A.; Delamater, N. D.; Wilson, D. C.; Guzik, Joyce A.; Haynes, D. A.; Gunderson, Michael A.; Klare, K. A.; Watt, R.; Wood, W. M.; Varnum, W. S.

doi:10.1017/s0263034605050330

Cited by 33 publications

(19 citation statements)

References 15 publications

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“…12,14,[29][30][31] The laser beams in each ring were equally spaced azimuthally, in order to maximize the azimuthal symmetry. 10 The laser pulse shape, a nominal 2 ns pulse with 150 ps rise, and fall times is shown for shot N130617 in Fig.…”

Section: Methodsmentioning

confidence: 99%

X-ray spectroscopic diagnostics and modeling of polar-drive implosion experiments on the National Ignition Facility

et al. 2014

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A series of experiments featuring laser-imploded plastic-shell targets filled with hydrogen or deuterium were performed on the National Ignition Facility. The shells (some deuterated) were doped in selected locations with Cu, Ga, and Ge, whose spectroscopic signals (indicative of local plasma conditions) were collected with a time-integrated, 1-D imaging, spectrally resolved, and absolute-intensity calibrated instrument. The experimental spectra compare well with radiation hydrodynamics simulations post-processed with a non-local thermal equilibrium atomic kinetics and spectroscopic-quality radiation-transport model. The obtained degree of agreement between the modeling and experimental data supports the application of spectroscopic techniques for the determination of plasma conditions, which can ultimately lead to the validation of theoretical models for thermonuclear burn in the presence of mix. Furthermore, the use of a lower-Z dopant element (e.g., Fe) is suggested for future experiments, since the ∼2 keV electron temperatures reached in mixed regions are not high enough to drive sufficient H-like Ge and Cu line emissions needed for spectroscopic plasma diagnostics.

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Section: Methodsmentioning

confidence: 99%

X-ray spectroscopic diagnostics and modeling of polar-drive implosion experiments on the National Ignition Facility

et al. 2014

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“…The targets-20-lm-thick, 865-lm-diam CH shells filled with 15 atm of D 2 -were imploded with a 1-ns temporally flat laser pulse containing $16 kJ of energy. Similar 40-beam configurations had been used earlier by Glendinning 340 and Kyrala et al 341 to diagnose approximately spherical implosions with x-ray backlighting.…”

Section: Polar-drive Implosionsmentioning

confidence: 84%

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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“…Double shell targets provide a very different approach to ICF than single shells [24][25][26][27][28][29][30] . Double shell targets consist of a low Z outer shell which separates the driver from the inner shell Developing one-dimensional implosions for inertial confinement fusion science filled with the fusion fuel.…”

Section: Double Shellsmentioning

confidence: 99%

Developing one-dimensional implosions for inertial confinement fusion science

Kline

Simakov

et al. 2016

High Pow Laser Sci Eng

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Experiments on the National Ignition Facility show that multi-dimensional effects currently dominate the implosion performance. Low mode implosion symmetry and hydrodynamic instabilities seeded by capsule mounting features appear to be two key limiting factors for implosion performance. One reason these factors have a large impact on the performance of inertial confinement fusion implosions is the high convergence required to achieve high fusion gains. To tackle these problems, a predictable implosion platform is needed meaning experiments must trade-off high gain for performance. LANL has adopted three main approaches to develop a one-dimensional (1D) implosion platform where 1D means measured yield over the 1D clean calculation. A high adiabat, low convergence platform is being developed using beryllium capsules enabling larger case-to-capsule ratios to improve symmetry. The second approach is liquid fuel layers using wetted foam targets. With liquid fuel layers, the implosion convergence can be controlled via the initial vapor pressure set by the target fielding temperature. The last method is double shell targets. For double shells, the smaller inner shell houses the DT fuel and the convergence of this cavity is relatively small compared to hot spot ignition. However, double shell targets have a different set of trade-off versus advantages. Details for each of these approaches are described.

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Direct drive double shell target implosion hydrodynamics on OMEGA

Cited by 33 publications

References 15 publications

X-ray spectroscopic diagnostics and modeling of polar-drive implosion experiments on the National Ignition Facility

X-ray spectroscopic diagnostics and modeling of polar-drive implosion experiments on the National Ignition Facility

Direct-drive inertial confinement fusion: A review

Developing one-dimensional implosions for inertial confinement fusion science

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