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Title: A 1D Analysis of Direct and Indirect Drive Target Performance for Planar Hydrodynamics Experiments on the NIF

Abstract

The 1D performance of laser or X-ray driven targets to study phenomena such as the Richtmyer-Meshkov instability in a single, steady shock, step down in density system has been described by a simple model based on 1D hydrodynamics. It is shown that the distance the interface travels under constant velocity conditions is a multiple of the separation between the ablation and shock front, and that this multiple depends on the density ratio at the interface, and the equations of states of the two materials. The model is applied to NIF with the aid of 1D hydrocode simulations to predict the ablation-shock separation. It is found that if adequate interface planarity can be maintained over an experimental length equal to the focal spot diameter, direct drive may out-perform indirect drive by up to {approx} factor 2 at the same pulse length and typically {ge} 2 at the same ablation pressure. This depends on the ability to control 2D effects in the directly driven targets (critically), and on the optimum hohlraum performance achievable for these experiments, rather than the achievable performance used for the study. It is predicted that several mm of constant velocity interface travel are potentially achievable on NIF, andmore » that this is only weakly dependent on the available energy. The 1D model and its application are described. Uncertainties surrounding the predictions are discussed, and means to resolve them outlined.« less

Authors:
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (US)
Sponsoring Org.:
USDOE Office of Defense Programs (DP) (US)
OSTI Identifier:
793580
Report Number(s):
UCRL-ID-139831
TRN: US200221%%205
DOE Contract Number:
W-7405-Eng-48
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 10 Jul 2000
Country of Publication:
United States
Language:
English
Subject:
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; ABLATION; EQUATIONS OF STATE; HYDRODYNAMICS; INSTABILITY; LASERS; PERFORMANCE; TARGETS; VELOCITY

Citation Formats

Edwards, M.J. A 1D Analysis of Direct and Indirect Drive Target Performance for Planar Hydrodynamics Experiments on the NIF. United States: N. p., 2000. Web. doi:10.2172/793580.
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Edwards, M.J. A 1D Analysis of Direct and Indirect Drive Target Performance for Planar Hydrodynamics Experiments on the NIF. United States. doi:10.2172/793580.
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Edwards, M.J. Mon . "A 1D Analysis of Direct and Indirect Drive Target Performance for Planar Hydrodynamics Experiments on the NIF". United States. doi:10.2172/793580. https://www.osti.gov/servlets/purl/793580.
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@article{osti_793580,
title = {A 1D Analysis of Direct and Indirect Drive Target Performance for Planar Hydrodynamics Experiments on the NIF},
author = {Edwards, M.J.},
abstractNote = {The 1D performance of laser or X-ray driven targets to study phenomena such as the Richtmyer-Meshkov instability in a single, steady shock, step down in density system has been described by a simple model based on 1D hydrodynamics. It is shown that the distance the interface travels under constant velocity conditions is a multiple of the separation between the ablation and shock front, and that this multiple depends on the density ratio at the interface, and the equations of states of the two materials. The model is applied to NIF with the aid of 1D hydrocode simulations to predict the ablation-shock separation. It is found that if adequate interface planarity can be maintained over an experimental length equal to the focal spot diameter, direct drive may out-perform indirect drive by up to {approx} factor 2 at the same pulse length and typically {ge} 2 at the same ablation pressure. This depends on the ability to control 2D effects in the directly driven targets (critically), and on the optimum hohlraum performance achievable for these experiments, rather than the achievable performance used for the study. It is predicted that several mm of constant velocity interface travel are potentially achievable on NIF, and that this is only weakly dependent on the available energy. The 1D model and its application are described. Uncertainties surrounding the predictions are discussed, and means to resolve them outlined.},
doi = {10.2172/793580},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jul 10 00:00:00 EDT 2000},
month = {Mon Jul 10 00:00:00 EDT 2000}
}
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DOI:  10.2172/793580
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