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Author:
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ISBN:
Category :
Languages : en
Pages : 9
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Book Description
The numerical tools typically used to model the evolution of fluid instabilities in inertial confinement fusion (ICF) hydrodynamics codes are examined, and some are found to have properties which would seem to be incompatible with the accurate modeling of small-amplitude perturbations, i.e., perturbations in the linear stage of evolution. In particular a "differentiability condition" which is satisfied by the physics in such situations is not necessarily satisfied by the numerical algorithms in typical use. It is demonstrated that it is possible to remove much of the non-differentiability in many cases, and that substantial improvement in one's ability to accurately model the evolution of small amplitude perturbations can result. First a simple example involving a non-differentiable radiation transport algorithm is shown, and then the non- differentiabilities introduced by the use of upwind and "high resolution" hydrodynamics algorithms are analyzed.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Book Description
The numerical tools typically used to model the evolution of fluid instabilities in inertial confinement fusion (ICF) hydrodynamics codes are examined, and some are found to have properties which would seem to be incompatible with the accurate modeling of small-amplitude perturbations, i.e., perturbations in the linear stage of evolution. In particular a "differentiability condition" which is satisfied by the physics in such situations is not necessarily satisfied by the numerical algorithms in typical use. It is demonstrated that it is possible to remove much of the non-differentiability in many cases, and that substantial improvement in one's ability to accurately model the evolution of small amplitude perturbations can result. First a simple example involving a non-differentiable radiation transport algorithm is shown, and then the non- differentiabilities introduced by the use of upwind and "high resolution" hydrodynamics algorithms are analyzed.
Author: Samuel Carl Miller
Publisher:
ISBN:
Category :
Languages : en
Pages : 169
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Book Description
"Performance degradation in laser direct-drive (LDD) inertial confinement fusion (ICF) implosions is caused by several effects, including Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) hydrodynamic instability growth. RT instability growth occurs in both the acceleration and deceleration phases of implosions. The first half of this thesis examines the evolution of internal perturbations that create seeds for instability growth during shock-transit (or early-time), while the second half describes the perturbation evolution during shell deceleration. During shock-transit, perturbations from shell material density modulations and isolated defects plant seeds at various interfaces such as the ablation front and material interfaces. These seeds can become amplified due to secular feedout growth and shock-induced vorticity and will grow exponentially during the acceleration phase due to ablative RT. A comprehensive understanding of this evolution is essential to characterize the impact of internal defects on inflight shell integrity. Through detailed simulations and analysis, this thesis identifies several key physical processes that play a role in the evolution of perturbations created by these defects throughout the early stage of implosions. Simulations also predict that significant shell mass modulations develop during shell acceleration. The use of low density ablator materials (foam) is suggested as a potential mitigation strategy to reduce the effects created by these defects. To perform this detailed study of internal defect evolution, two new high-fidelity physics codes were developed to track characteristic wave propagation in the ICF context using low-noise, low-dissipation, high-order spatial accuracy solution methods. Modern high performance computing (HPC) systems have becoming increasingly complex, and adapting existing or new software to fully utilize them is a significant development challenge. Each code in this thesis examines the feasibility of different approaches: a modern design in a well-known HPC-centric language (Fortran), and a new language (Julia), which emphasizes developer productivity and shows the potential to be well-suited for HPC workloads. Mass modulations at the ablation front, which grow during the acceleration phase, feed through to the inner surface of the shell and create seeds for deceleration phase RT growth at the inner surface. Deceleration instability growth was studied using laser direct drive implosions of room-temperature plastic targets. Perturbation growth in such implosions is enhanced by the density discontinuity and finite Atwood number at the fuel-shell interface. The magnitude of this density discontinuity can be controlled by changing the fuel composition (D:T, or ratio of deuterium to tritium). However, this thesis demonstrates that the stability of the interface is best characterized by the effective Atwood number, which is primarily determined by material densities at distances on the order of perturbation wavelength on either side of the interface, rather than the density ratio at the interface. Since the densities at these distances are defined not by fuel composition, but radiation heating of the shell, both simulation and experimental data show that target performance is insensitive to different D:T ratios"--Pages ix -x
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309270626
Category : Science
Languages : en
Pages : 119
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Book Description
In the fall of 2010, the Office of the U.S. Department of Energy's (DOE's) Secretary for Science asked for a National Research Council (NRC) committee to investigate the prospects for generating power using inertial confinement fusion (ICF) concepts, acknowledging that a key test of viability for this concept-ignition -could be demonstrated at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) in the relatively near term. The committee was asked to provide an unclassified report. However, DOE indicated that to fully assess this topic, the committee's deliberations would have to be informed by the results of some classified experiments and information, particularly in the area of ICF targets and nonproliferation. Thus, the Panel on the Assessment of Inertial Confinement Fusion Targets ("the panel") was assembled, composed of experts able to access the needed information. The panel was charged with advising the Committee on the Prospects for Inertial Confinement Fusion Energy Systems on these issues, both by internal discussion and by this unclassified report. A Panel on Fusion Target Physics ("the panel") will serve as a technical resource to the Committee on Inertial Confinement Energy Systems ("the Committee") and will prepare a report that describes the R&D challenges to providing suitable targets, on the basis of parameters established and provided to the Panel by the Committee. The Panel on Fusion Target Physics will prepare a report that will assess the current performance of fusion targets associated with various ICF concepts in order to understand: 1. The spectrum output; 2. The illumination geometry; 3. The high-gain geometry; and 4. The robustness of the target design. The panel addressed the potential impacts of the use and development of current concepts for Inertial Fusion Energy on the proliferation of nuclear weapons information and technology, as appropriate. The Panel examined technology options, but does not provide recommendations specific to any currently operating or proposed ICF facility.
Author: Rupak Biswas
Publisher: DEStech Publications, Inc
ISBN: 160595022X
Category : Computers
Languages : en
Pages : 703
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Book Description
Author:
Publisher:
ISBN:
Category : Inertial confinement fusion
Languages : en
Pages : 64
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Book Description
Author: James J. Duderstadt
Publisher: John Wiley & Sons
ISBN:
Category : Science
Languages : en
Pages : 380
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Book Description
Author: Ye Zhou
Publisher: Cambridge University Press
ISBN: 1108489648
Category : Mathematics
Languages : en
Pages : 611
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Book Description
The first comprehensive reference guide to turbulent mixing driven by Rayleigh-Taylor, Richtmyer-Meshkov and Kelvin-Helmholtz instabilities.
Author: Jean-Claude Gauthier
Publisher:
ISBN:
Category : Controlled fusion
Languages : en
Pages : 1288
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Book Description
Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 836
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Book Description
Author: Stefano Atzeni
Publisher: OUP Oxford
ISBN: 9780191524059
Category : Science
Languages : en
Pages : 488
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Book Description
This book is on inertial confinement fusion, an alternative way to produce electrical power from hydrogen fuel by using powerful lasers or particle beams. It involves the compression of tiny amounts (micrograms) of fuel to thousand times solid density and pressures otherwise existing only in the centre of stars. Thanks to advances in laser technology, it is now possible to produce such extreme states of matter in the laboratory. Recent developments have boosted laser intensities again with new possibilities for laser particle accelerators, laser nuclear physics, and fast ignition of fusion targets. This is a reference book for those working on beam plasma physics, be it in the context of fundamental research or applications to fusion energy or novel ultra-bright laser sources. The book combines quite different areas of physics: beam target interaction, dense plasmas, hydrodynamic implosion and instabilities, radiative energy transfer as well as fusion reactions. Particular attention is given to simple and useful modelling, including dimensional analysis and similarity solutions. Both authors have worked in this field for more than 20 years. They want to address in particular those teaching this topic to students and all those interested in understanding the technical basis.
