SIMULTANEOUS VISAR AND TXD MEASUREMENTS ON SHOCKS IN BERYLLIUM CRYSTALS
- Damian C.
Shock waves were induced in single crystals of beryllium, by direct illumination using the TRIDENT laser at Los Alamos. The velocity history at the surface was measured using a line-imaging VISAR, and transient X-ray diffraction (TXD) records were obtained with a plasma backlighter and X-ray streak camera. At lower pressures, the VISAR records exhibited an elastic precursor followed by a plastic wave and spall. At higher pressure, the velocity records showed a two-wave structure suggesting a phase change, then at the highest pressure a single broad wave suggesting a shock directly into the high pressure phase. The rocking curves of the crystals were typically about 2 degrees wide, so analysis of the TXD records is complicated by the relatively large amount of blurring. However the Bragg record of the shocked 0002 peak clearly indicates a smaller lattice parameter at higher pressure. In the shots where polymorphism seemed to appear in the VISAR record, additional lines appeared in the bragg record, and new lines also appeared within the field of view of the Laue camera. These results are consistent with a new quantum mechanical equation of state for beryllium, which suggests that the hexagonal to body-centered cubic transition occurs at {approx}40 GPa on the principal Hugoniot.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 975579
- Report Number(s):
- LA-UR-01-3407; TRN: US201018%%767
- Resource Relation:
- Journal Volume: 620; Conference: Submitted to: Proc American Physical Society Topical Conference on Shock Compression of Condensed Matter, to be held Atlanta, GA, 25 to 29 June 2001.
- Country of Publication:
- United States
- Language:
- English
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