Statistical modeling of experimental and simulation databases has enabled the development of an accurate predictive capability for deuterium-tritium layered cryogenic implosions at the OMEGA laser V. ...Gopalaswamy et al.,Nature 565, 581 (2019). In this letter, a physics-based statistical mapping framework is described and used to uncover the dependencies of the fusion yield. This model is used to identify and quantify the degradation mechanisms of the fusion yield in direct-drive implosions on OMEGA. The yield is found to be reduced by the ratio of laser beam to target radius, the asymmetry in inferred ion temperatures from the ℓ = 1 mode, the time span over which tritium fuel has decayed, and parameters related to the implosion hydrodynamic stability. When adjusted for tritium decay and ℓ = 1 mode, the highest yield in OMEGA cryogenic implosions is predicted to exceed 2 × 1014 fusion reactions.
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An analytical model of the nonlinear bubble evolution of single-mode, classical Rayleigh-Taylor instability at arbitrary Atwood numbers (A(T)) is presented. The model is based on an extension of ...Layzer's theory Astrophys. J. 122, 1 (1955) previously applied only to the fluid-vacuum interfaces (A(T) = 1). The model provides a continuous bubble evolution from the earlier exponential growth to the nonlinear regime when the bubble velocity saturates at U(b) = square root of 2A(T)/(1+A(T)) (g/C(g)k), where k is the perturbation wave number, g is the interface acceleration, and C(g) = 3 and C(g) = 1 for the two-dimensional and three-dimensional geometries, respectively.
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A new class of ignition designs is proposed for inertial confinement fusion experiments. These designs are based on the hot-spot ignition approach, but instead of a conventional target that is ...comprised of a spherical shell with a thin frozen deuterium-tritium (DT) layer, a liquid DT sphere inside a wetted-foam shell is used, and the lower-density central region and higher-density shell are created dynamically by appropriately shaping the laser pulse. These offer several advantages, including simplicity in target production (suitable for mass production for inertial fusion energy), absence of the fill tube (leading to a more-symmetric implosion), and lower sensitivity to both laser imprint and physics uncertainty in shock interaction with the ice-vapor interface. The design evolution starts by launching an ∼ 1 -Mbar shock into a DT sphere. After bouncing from the center, the reflected shock reaches the outer surface of the sphere and the shocked material starts to expand outward. Supporting ablation pressure ultimately stops such expansion and subsequently launches a shock toward the target center, compressing the ablator and fuel, and forming a shell. The shell is then accelerated and fuel is compressed by appropriately shaping the drive laser pulse, forming a hot spot using the conventional or shock ignition approaches. This Letter demonstrates the feasibility of the new concept using hydrodynamic simulations and discusses the advantages and disadvantages of the concept compared with more-traditional inertial confinement fusion designs.
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Accurate knowledge about the equation of state (EOS) of deuterium is critical to inertial confinement fusion (ICF). Low-adiabat ICF implosions routinely access strongly coupled and degenerate plasma ...conditions. Using the path integral Monte Carlo method, we have derived a first-principles EOS (FPEOS) table of deuterium. It is the first ab initio EOS table which completely covers typical ICF implosion trajectory in the density and temperature ranges of ρ=0.002-1596 g/cm3 and T=1.35 eV-5.5 keV. Discrepancies in internal energy and pressure have been found in strongly coupled and degenerate regimes with respect to SESAME EOS. Hydrodynamics simulations of cryogenic ICF implosions using the FPEOS table have indicated significant differences in peak density, areal density (ρR), and neutron yield relative to SESAME simulations.
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Radiation-hydrodynamic simulations of directly driven fusion experiments at the Omega Laser Facility predict absorption accurately when targets are driven at low overlapped laser intensity. ...Discrepancies appear at increased intensity, however, with higher-than-expected laser absorption on target. Strong correlations with signatures of the two-plasmon decay (TPD) instability-including half-harmonic and hard-x-ray emission-indicate that TPD is responsible for this anomalous absorption. Scattered light data suggest that up to ≈30% of the laser power reaching quarter-critical density can be absorbed locally when the TPD threshold is exceeded. A scaling of absorption versus TPD threshold parameter was empirically determined and validated using the laser-plasma simulation environment code.
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The material release on the side opposite to the laser drive of a CH shell was probed at conditions relevant to inertial confinement fusion. The release was found to expand further with a longer ...scale length than that predicted by radiation-hydrodynamic simulations. The simulations show that a relaxation of the back side of the shell consistent with measurements explains the experimentally observed reduction in inertial confinement fusion implosion performance-specifically, reduced areal density at peak compression.
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Spherical implosions in Inertial Confinement Fusion (ICF) are inherently sensitive to perturbations that may arise from experimental constraints and errors. Control and mitigation of low-mode (long ...wavelengths) perturbations is a key milestone to improving implosion performances. We present the first 3-D radiation-hydrodynamic simulations of directly driven ICF implosions with an inline package for polarized Crossed-Beam Energy Transfer (CBET). Simulations match bang times, yields (separately accounting for laser-induced high modes and fuel age), hot spot flow velocities and direction, for which polarized CBET contributes to the systematic flow orientation evident in the OMEGA implosion database. Current levels of beam mispointing, imbalance, target offset and asymmetry from polarized CBET degrade yields by more than 40%. The effectiveness of two mitigation strategies for low-modes is explored
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The article aims at revising Durkheim’s pejorative assessment of utilitarianhedonistic impulses as the reasons for the differentiation of labor in the consumerism perspective. The author considers ...Durkheim’s criticism of economism and utilitarianism through his theory of social solidarity as having moral rather than utilitarian foundations and shows the transformation of Durkheim’s concept of solidarism and the idea of division of labor based on it in social practices of the contemporary consumer society. Thus, the concentration of morality in the rules (according to Durkheim) that regulate social behavior proves that the rules and morality of the consumer society are determined by consumerist values and make every individual play the consumer role. The inconsistency of solidarism under consumerism is expressed in the fact that, despite the high degree of social integration which demands that as an organic part of the social we have to ‘sacrifice’ ourselves to this whole, in the consumer society, there is a reverse trend - the dominance of consumer values, attitudes and stereotypes which determine models of social behavior based on selfishness. In the second part of the article, the author considers utilitarian-hedonistic needs multiplied by consumerism as one of the key reasons for the progress and differentiation of labor. Hedonistic intentions manifested in consumer practices should be considered not as mental or psychological (according to Durkheim) but as social facts. The author argues that Durkheim’s concept of social solidarity, which seeks to overcome economism and utilitarianism in the interpretation of the progress of labor, may be of scientific interest as an alternative (moral) approach. However, it ignores the potential of the permanent desire for pleasure in the social-cultural environment of consumerism; therefore, in the consumer society with appropriate morality, this approach loses to the utilitarianeconomic interpretation of the progress of labor. One of Durkheim’s main arguments in the critique of the hedonistic and eudemonistic causality of the progress of labor is that if the differentiation of labor aimed at increasing happiness and pleasure, then this progress would have reached its limits long ago, but the contemporary consumer society proves the opposite.
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