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Title: A geophysical shock and air blast simulator at the National Ignition Facility

Abstract

The energy partitioning energy coupling experiments at the National Ignition Facility (NIF) have been designed to measure simultaneously the coupling of energy from a laser-driven target into both ground shock and air blast overpressure to nearby media. The source target for the experiment is positioned at a known height above the ground-surface simulant and is heated by four beams from the NIF. The resulting target energy density and specific energy are equal to those of a low-yield nuclear device. The ground-shock stress waves and atmospheric overpressure waveforms that result in our test system are hydrodynamically scaled analogs of full-scale seismic and air blast phenomena. This report summarizes the development of the platform, the simulations, and calculations that underpin the physics measurements that are being made, and finally the data that were measured. Agreement between the data and simulation of the order of a factor of two to three is seen for air blast quantities such as peak overpressure. Historical underground test data for seismic phenomena measured sensor displacements; we measure the stresses generated in our ground-surrogate medium. We find factors-of-a-few agreement between our measured peak stresses and predictions with modern geophysical computer codes.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [2];  [2]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. National Security Technologies, Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1165736
DOE Contract Number:
AC52-07NA27344
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 9
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUMM MECHANICS, GENERAL PHYSICS; BLAST WAVES; PRESSURE MEASUREMENT; QUARTZ; ATMOSPHERIC PRESSURE; SEISMIC SOURCES

Citation Formats

Fournier, K. B., Brown, C. G., May, M. J., Compton, S., Walton, O. R., Shingleton, N., Kane, J. O., Holtmeier, G., Loey, H., Mirkarimi, P. B., Dunlop, W. H., Guyton, R. L., and Huffman, E.. A geophysical shock and air blast simulator at the National Ignition Facility. United States: N. p., 2014. Web. doi:10.1063/1.4896119.
Fournier, K. B., Brown, C. G., May, M. J., Compton, S., Walton, O. R., Shingleton, N., Kane, J. O., Holtmeier, G., Loey, H., Mirkarimi, P. B., Dunlop, W. H., Guyton, R. L., & Huffman, E.. A geophysical shock and air blast simulator at the National Ignition Facility. United States. doi:10.1063/1.4896119.
Fournier, K. B., Brown, C. G., May, M. J., Compton, S., Walton, O. R., Shingleton, N., Kane, J. O., Holtmeier, G., Loey, H., Mirkarimi, P. B., Dunlop, W. H., Guyton, R. L., and Huffman, E.. Mon . "A geophysical shock and air blast simulator at the National Ignition Facility". United States. doi:10.1063/1.4896119. https://www.osti.gov/servlets/purl/1165736.
@article{osti_1165736,
title = {A geophysical shock and air blast simulator at the National Ignition Facility},
author = {Fournier, K. B. and Brown, C. G. and May, M. J. and Compton, S. and Walton, O. R. and Shingleton, N. and Kane, J. O. and Holtmeier, G. and Loey, H. and Mirkarimi, P. B. and Dunlop, W. H. and Guyton, R. L. and Huffman, E.},
abstractNote = {The energy partitioning energy coupling experiments at the National Ignition Facility (NIF) have been designed to measure simultaneously the coupling of energy from a laser-driven target into both ground shock and air blast overpressure to nearby media. The source target for the experiment is positioned at a known height above the ground-surface simulant and is heated by four beams from the NIF. The resulting target energy density and specific energy are equal to those of a low-yield nuclear device. The ground-shock stress waves and atmospheric overpressure waveforms that result in our test system are hydrodynamically scaled analogs of full-scale seismic and air blast phenomena. This report summarizes the development of the platform, the simulations, and calculations that underpin the physics measurements that are being made, and finally the data that were measured. Agreement between the data and simulation of the order of a factor of two to three is seen for air blast quantities such as peak overpressure. Historical underground test data for seismic phenomena measured sensor displacements; we measure the stresses generated in our ground-surrogate medium. We find factors-of-a-few agreement between our measured peak stresses and predictions with modern geophysical computer codes.},
doi = {10.1063/1.4896119},
journal = {Review of Scientific Instruments},
number = 9,
volume = 85,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}
  • The energy partitioning energy coupling experiments at the National Ignition Facility (NIF) have been designed to measure simultaneously the coupling of energy from a laser-driven target into both ground shock and air blast overpressure to nearby media. The source target for the experiment is positioned at a known height above the ground-surface simulant and is heated by four beams from the NIF. The resulting target energy density and specific energy are equal to those of a low-yield nuclear device. The ground-shock stress waves and atmospheric overpressure waveforms that result in our test system are hydrodynamically scaled analogs of full-scale seismicmore » and air blast phenomena. This report summarizes the development of the platform, the simulations, and calculations that underpin the physics measurements that are being made, and finally the data that were measured. Agreement between the data and simulation of the order of a factor of two to three is seen for air blast quantities such as peak overpressure. Historical underground test data for seismic phenomena measured sensor displacements; we measure the stresses generated in our ground-surrogate medium. We find factors-of-a-few agreement between our measured peak stresses and predictions with modern geophysical computer codes.« less
  • A high-performance inertial confinement fusion capsule is compressed by multiple shock waves before it implodes. To minimize the entropy acquired by the fuel, the strength and timing of those shock waves must be accurately controlled. Ignition experiments at the National Ignition Facility (NIF) will employ surrogate targets designed to mimic ignition targets while making it possible to measure the shock velocities inside the capsule. A series of experiments on the OMEGA laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)] validated those targets and the diagnostic techniques proposed. Quartz was selected for the diagnostic window and shock-velocity measurements weremore » demonstrated in Hohlraum targets heated to 180 eV. Cryogenic experiments using targets filled with liquid deuterium further demonstrated the entire timing technique in a Hohlraum environment. Direct-drive cryogenic targets with multiple spherical shocks were used to further validate this technique, including convergence effects at relevant pressures (velocities) and sizes. These results provide confidence that shock velocity and timing can be measured in NIF ignition targets, allowing these critical parameters to be optimized.« less
  • A scaled Hohlraum platform was used to experimentally measure preheat in ablator materials during the first few nanoseconds of a radiation drive proposed for ignition experiments at the National Ignition Facility [J. A. Paisner et al., Laser Focus World 30, 75 (1994)]. The platform design approximates the radiation environment of the pole of the capsule by matching both the laser spot intensity and illuminated Hohlraum wall fraction in scaled halfraums driven by the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. Back surface motion measured via VISAR reflecting from the rear surface of the samplemore » was used to measure sample motion prior to shock breakout. The experiments show that the first {approx}20 {mu}m of a Be ablator will be melted by radiation preheat, with subsequent material melted by the initial shock, in agreement with simulations. The experiments also show no evidence of anomalous heating of buried high-Z doped layers in the ablator.« less