Indirect-Drive Noncryogenic Double-Shell Ignition Targets for the National Ignition Facility

Indirect-Drive Noncryogenic Double-Shell Ignition Targets for the National Ignition Facility
Title Indirect-Drive Noncryogenic Double-Shell Ignition Targets for the National Ignition Facility PDF eBook
Author
Publisher
Pages
Release 2001
Genre
ISBN

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The central goal of the National Ignition Facility (NIF) is demonstration of controlled thermonuclear ignition. The mainline ignition target is a low-Z, single-shell cryogenic capsule designed to have weakly nonlinear Rayleigh-Taylor growth of surface perturbations. Double-shell targets are an alternative design concept that avoids the complexity of cryogenic preparation but has greater physics uncertainties associated with performance-degrading mix. A typical double-shell design involves a high-Z inner capsule filled with DT gas and supported within a low-Z ablator shell. The largest source of uncertainty for this target is the degree of highly evolved nonlinear mix on the inner surface of the high-Z shell. High Atwood numbers and feed-through of strong outer surface perturbation growth to the inner surface promote high levels of instability. The main challenge of the double-shell target designs is controlling the resulting nonlinear mix to levels that allow ignition to occur. Design and analysis of a suite of indirect-drive NIF double-shell targets with hohlraum temperatures of 200 eV and 250 eV are presented. Analysis of these targets includes assessment of two-dimensional radiation asymmetry as well as nonlinear mix. Two-dimensional integrated hohlraum simulations indicate that the x-ray illumination can be adjusted to provide adequate symmetry control in hohlraums specially designed to have high laser-coupling efficiency [Suter et al., Phys. Plasmas 5, 2092 (2000)]. These simulations also reveal the need to diagnose and control localized 10-15 keV x-ray emission from the high-Z hohlraum wall because of strong absorption by the high-Z inner shell. Preliminary estimates of the degree of laser backscatter from an assortment of laser-plasma interactions suggest comparatively benign hohlraum conditions. Application of a variety of nonlinear mix models and phenomenological tools, including buoyancy-drag models, multimode simulations and fall-line optimization, indicates a possibility of achieving ignition, i.e., fusion yields greater than 1 MJ. Planned experiments on the Omega laser to test current understanding of high-energy radiation flux asymmetry and mix-induced yield degradation in double-shell targets are described.

Direct Drive Double Shell Target Implosion Hydodynamics on OMEGA.

Direct Drive Double Shell Target Implosion Hydodynamics on OMEGA.
Title Direct Drive Double Shell Target Implosion Hydodynamics on OMEGA. PDF eBook
Author
Publisher
Pages 7
Release 2004
Genre
ISBN

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Imploding indirect-drive double shell targets may provide an alternative, non-cryogenic path to ignition on the National Ignition Facility (NIF). Experiments are being pursued at OMEGA to understand the hydrodynamics of these implosions and the possibility of scaling to NIF designs. We have used 40 beams from the OMEGA laser to directly drive the capsules, and we have used the remaining 20 beams to backlight the imploding shells from two different directions at multiple times. We will review the recent experiments to measure the hydrodynamics of the targets using two-view x-ray radiography of the capsules. We will present data on measured yields from the targets. We will present a measured time history of the hydrodynamics of the implosion. Experiments were pursued using direct drive in which the M-band effect, experienced in the indirect drive experiments, could be eliminated or controlled. It was learned in the direct drive experiments that the best performing capsules were those that had a thin outer layer of gold. This effectively causes M-band pre-heat effects giving implosion hydrodynamics and performance closer to the indirect drive case. We will review the method used to radiograph the targets and the techniques used to extract useful information to compare with calculations. The effect of imperfections in the target construction will be shown to be minimal during the initial stage of the implosion. The yields from the targets were observed to be uniformly low compared to indirect-drive.

Hydrodynamic Instabilities and Turbulence

Hydrodynamic Instabilities and Turbulence
Title Hydrodynamic Instabilities and Turbulence PDF eBook
Author Ye Zhou
Publisher Cambridge University Press
Pages 611
Release 2024-05-31
Genre Mathematics
ISBN 1108489648

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The first comprehensive reference guide to turbulent mixing driven by Rayleigh-Taylor, Richtmyer-Meshkov and Kelvin-Helmholtz instabilities.

Turbulence Modelling Approaches

Turbulence Modelling Approaches
Title Turbulence Modelling Approaches PDF eBook
Author Konstantin Volkov
Publisher BoD – Books on Demand
Pages 252
Release 2017-07-26
Genre Science
ISBN 9535133497

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Accurate prediction of turbulent flows remains a challenging task despite considerable work in this area and the acceptance of CFD as a design tool. The quality of the CFD calculations of the flows in engineering applications strongly depends on the proper prediction of turbulence phenomena. Investigations of flow instability, heat transfer, skin friction, secondary flows, flow separation, and reattachment effects demand a reliable modelling and simulation of the turbulence, reliable methods, accurate programming, and robust working practices. The current scientific status of simulation of turbulent flows as well as some advances in computational techniques and practical applications of turbulence research is reviewed and considered in the book.

Double-shell Target Design for the NIF: Noncryogenic Ignition and Nonlinear Mix Studies for Stockpile Stewardship

Double-shell Target Design for the NIF: Noncryogenic Ignition and Nonlinear Mix Studies for Stockpile Stewardship
Title Double-shell Target Design for the NIF: Noncryogenic Ignition and Nonlinear Mix Studies for Stockpile Stewardship PDF eBook
Author
Publisher
Pages
Release 2005
Genre
ISBN

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Abstract not provided.

Inertial Fusion Sciences and Applications 2003

Inertial Fusion Sciences and Applications 2003
Title Inertial Fusion Sciences and Applications 2003 PDF eBook
Author B. A. Hammel
Publisher
Pages 1158
Release 2004
Genre Controlled fusion
ISBN

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Annual Research Briefs ...

Annual Research Briefs ...
Title Annual Research Briefs ... PDF eBook
Author Center for Turbulence Research (U.S.)
Publisher
Pages 486
Release 2009
Genre Turbulence
ISBN

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