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Title: Simulations of NOVA direct-drive hydrodynamics experiments

Abstract

Directly driven Rayleigh-Taylor instability growth experiments being performed on NOVA have been simulated using the computer code, LASNEX. Foils with single-wavelength imposed surface perturbations have been driven with a single beam of 0.53 {mu}m light, employing smoothing by spectral dispersion (SSD). In addition to simulating foils with imposed surface perturbations, we have simulated flat foils driven by beams with time-dependent intensity modulation resulting from the NOVA implementation of SSD. These simulations show the development of large amplitude modulation of the target from residual intensity nonuniformities. Structure seeded by beam nonuniformity would overwhelm modulation resulting from imposed surface perturbations of sub-micron initial amplitude, but is predicted to develop sufficiently slowly that we expect to observe growth of perturbations with initial amplitudes of several microns. In other NOVA experiments, flat foils with an embedded brominated spectroscopic tracer layer are used in infer mass ablation rates. SSD drive is predicted to yield ablation rates in better agreement with 1-D simulations than drive from a beam with random phase plates (RPP) alone. Simulations of foils driven with RPP beams show enhanced ablation rates because modulation of the ablation front increases its surface area. Line emission from the seed is first seen at cold spotsmore » in the beam, which create protruding spikes at the ablation front. Simulation results will be compared with early experimental data. 5 refs., 14 figs.« less

Authors:
;
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (USA)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (USA)
OSTI Identifier:
5829917
Report Number(s):
UCRL-JC-104372-R1; CONF-9104241-2-Rev.1
ON: DE91012078
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: 21. annual anomalous absorption conference, Banff (Canada), 15-19 Apr 1991
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; LASER TARGETS; RAYLEIGH-TAYLOR INSTABILITY; COMPUTERIZED SIMULATION; ABLATION; DESIGN; HYDRODYNAMICS; INSTABILITY GROWTH RATES; L CODES; NOVA FACILITY; COMPUTER CODES; FLUID MECHANICS; INSTABILITY; MECHANICS; SIMULATION; TARGETS; 700208* - Fusion Power Plant Technology- Inertial Confinement Technology

Citation Formats

Weber, S V, and Glendinning, S G. Simulations of NOVA direct-drive hydrodynamics experiments. United States: N. p., 1991. Web.
Weber, S V, & Glendinning, S G. Simulations of NOVA direct-drive hydrodynamics experiments. United States.
Weber, S V, and Glendinning, S G. Mon . "Simulations of NOVA direct-drive hydrodynamics experiments". United States. https://www.osti.gov/servlets/purl/5829917.
@article{osti_5829917,
title = {Simulations of NOVA direct-drive hydrodynamics experiments},
author = {Weber, S V and Glendinning, S G},
abstractNote = {Directly driven Rayleigh-Taylor instability growth experiments being performed on NOVA have been simulated using the computer code, LASNEX. Foils with single-wavelength imposed surface perturbations have been driven with a single beam of 0.53 {mu}m light, employing smoothing by spectral dispersion (SSD). In addition to simulating foils with imposed surface perturbations, we have simulated flat foils driven by beams with time-dependent intensity modulation resulting from the NOVA implementation of SSD. These simulations show the development of large amplitude modulation of the target from residual intensity nonuniformities. Structure seeded by beam nonuniformity would overwhelm modulation resulting from imposed surface perturbations of sub-micron initial amplitude, but is predicted to develop sufficiently slowly that we expect to observe growth of perturbations with initial amplitudes of several microns. In other NOVA experiments, flat foils with an embedded brominated spectroscopic tracer layer are used in infer mass ablation rates. SSD drive is predicted to yield ablation rates in better agreement with 1-D simulations than drive from a beam with random phase plates (RPP) alone. Simulations of foils driven with RPP beams show enhanced ablation rates because modulation of the ablation front increases its surface area. Line emission from the seed is first seen at cold spots in the beam, which create protruding spikes at the ablation front. Simulation results will be compared with early experimental data. 5 refs., 14 figs.},
doi = {},
url = {https://www.osti.gov/biblio/5829917}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1991},
month = {4}
}

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