Nova Experiments Examining Raleigh-Taylor Instability in Materials with Strength
Material strength can affect the growth of the Rayleigh-Taylor instability in solid materials, where growth occurs through plastic flow. In order to study this effect at megabar pressures, we have shocked metal foils using hohlraum x-ray drive on Nova, and observed the growth of pre-imposed modulations with x-ray radiography. Previous experiments employing Cu foils did not conclusively show strength effects for resolvable wavelengths. Therefore, we have redesigned the experiment to use aluminum foils. As aluminum has higher specific strength at pressures {approx}1 Mbar, the new design is predicted to show growth reduction due to strength of at least a factor of two for some wavelengths in the observable range of 10 - 50 {micro}m. We have also modified the drive history to extend the interval of uniform acceleration and to reduce the risk of melting the foils with coalesced shocks. The design changes, as well as Nova operational constraints, limit peak pressures to 1-1.5 Mbar. Foil surface motion has been measured with high sensitivity by laser interferometry to look for thermal expansion due to preheat. We have continued to pursue dynamic x-ray diffraction as the most definitive measurement of crystal state.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Office of Defense Programs (DP) (US)
- DOE Contract Number:
- W-7405-Eng-48
- OSTI ID:
- 792361
- Report Number(s):
- UCRL-JC-132739; TRN: US200223%%570
- Resource Relation:
- Conference: 7th International Workshop on the Physics of Compressible Turbulent Mixing Russian Federal Nuclear Center - Institute of Experimental Physics, St. Petersburg (RU), 07/05/1999--07/09/1999; Other Information: PBD: 6 Oct 1999
- Country of Publication:
- United States
- Language:
- English
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