Shock formation and the ideal shape of ramp compression waves

Swift, Damian; Kraus, R. G.; Loomis, Eric; Hicks, D. G.; McNaney, J. M.; Johnson, R. P.

doi:10.1103/physreve.78.066115

Cited by 46 publications

(31 citation statements)

References 20 publications

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“…Temporal laser pulse shaping was used to optimize the ramp profile using a model based on [12,13] resulting in an exponential type laser profile. To ensure a uniform compression front, a Hybrid Phase Plate (HPP) was used to obtain a smooth flat laser profile of 1 mm-diameter, considerably larger than the sample thickness, which implies conditions of uniaxial strain during the measurement.…”

Section: Methodsmentioning

confidence: 99%

Laser-Driven Ramp Compression to Investigate and Model Dynamic Response of Iron at High Strain Rates

Amadou

Brambrink

Rességuier

et al. 2016

Metals

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Efficient laser shock processing of materials requires a good characterization of their dynamic response to pulsed compression, and predictive numerical models to simulate the thermomechanical processes governing this response. Due to the extremely high strain rates involved, the kinetics of these processes should be accounted for. In this paper, we present an experimental investigation of the dynamic behavior of iron under laser driven ramp loading, then we compare the results to the predictions of a constitutive model including viscoplasticity and a thermodynamically consistent description of the bcc to hcp phase transformation expected near 13 GPa. Both processes are shown to affect wave propagation and pressure decay, and the influence of the kinetics of the phase transformation on the velocity records is discussed in details.

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Section: Methodsmentioning

confidence: 99%

Laser-Driven Ramp Compression to Investigate and Model Dynamic Response of Iron at High Strain Rates

Amadou

Brambrink

Rességuier

et al. 2016

Metals

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“…[660][661][662][663] Ramp compression can be achieved by driving a target with the forward-moving ejecta that are released from a shock-compressed material 664 or with a slowly rising laser pulse that acts to continually increase the pressure on the target. [665][666][667][668] By controlling the rate of rise, one can ensure that the waves of increasing compression will not overtake earlier ones, producing a shockless compression of the material. Diamond is a favored material because its high strength allows it to be compressed without shocks.…”

Section: Equation Of Statementioning

confidence: 99%

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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“…In real ICEs, shock wave transitions often occur midway on the loading pressure history rather than on their fronts. Aside from the expression mentioned above, there are two more improved RST conditions given by Swift et al 3 One is in Lagrangian form, the another in Eulerian form. From the Lagrangian form, Eq.…”

Section: Comparison With Previous Workmentioning

confidence: 99%

“…The equation of state (EOS) for condensed matter at extreme pressures is an important issue in geoplanetary physics, condensed state physics, and many related fields. 1 Two widely used approaches to measure dynamic compressibility and EOS parameters of materials are shock compression, by either planar flyer impact or laser-induced shock wave, and isentropic compression using expanding gases from the detonation of chemical explosives, 2 graded density impactors, 3 magnetic pressure loading, 4-7 loading by an expanding plume of vapor generated by laser-ablated samples, 8 or separate "pressure reservoir" films. 9 Shock compression in metals can attain multi-Mbar pressures, even above 1 TPa pressures, [10][11][12][13] but generate simultaneously high elevated temperatures in samples.…”

mentioning

confidence: 99%

“…Thus optimizing the loading pressure waveforms of ICEs is important in avoiding as much as possible any shock wave transition and rise in peak pressure. Davis et al 1 and Swift et al 3 reported their theoretical investigations on the condition for ramp-toshock transition (RST) to occur and related optimized loading pressure waveforms. Davis et al derived criteria by which the formation of the shock on the first characteristic can be avoided, as a necessary condition in constructing a complete ramp profile, for any EOS.…”

mentioning

confidence: 99%

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