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Title: Shock Propagation and Instability Structures in Compressed Silica Aerogels

We have performed a series of experiments examining shock propagation in low density aerogels. High-pressure ({approx}100 kbar) shock waves are produced by detonating high explosives. Radiography is used to obtain a time sequence imaging of the shocks as they enter and traverse the aerogel. We compress the aerogel by impinging shocks waves on either one or both sides of an aerogel slab. The shock wave initially transmitted to the aerogel is very narrow and flat, but disperses and curves as it propagates. Optical images of the shock front reveal the initial formation of a hot dense region that cools and evolves into a well-defined microstructure. Structures observed in the shock front are examined in the framework of hydrodynamic instabilities generated as the shock traverses the low-density aerogel. The primary features of shock propagation are compared to simulations, which also include modeling the detonation of the high explosive, with a 2-D Arbitrary Lagrange Eulerian hydrodynamics code The code includes a detailed thermochemical equation of state and rate law kinetics. We will present an analysis of the data from the time resolved imaging diagnostics and form a consistent picture of the shock transmission, propagation and instability structure.
Authors:
; ; ; ;
Publication Date:
OSTI Identifier:
15005397
Report Number(s):
UCRL-JC-146894
TRN: US0305368
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: International Workshop, New Models and Hydrocodes for Shock Wave Processes in Condensed Matter, Edinburgh (GB), 05/19/2002--05/24/2002; Other Information: PBD: 30 May 2002
Research Org:
Lawrence Livermore National Lab., CA (US)
Sponsoring Org:
US Department of Energy (US)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; HYDRODYNAMICS; INSTABILITY; KINETICS; MICROSTRUCTURE; SHOCK WAVES; SILICA; WAVE PROPAGATION; GELS; COMPUTERIZED SIMULATION