High-Pressure Tailored Compression: Controlled Thermodynamic Paths
We have recently carried out novel and exploratory dynamic experiments where the sample follows a prescribed thermodynamic path. In typical dynamic compression experiments, the samples are thermodynamically limited to the principal Hugoniot or quasi-isentrope. With recent developments in the functionally graded material impactor, we can prescribe and shape the applied pressure profile with similarly-shaped, non-monotonic impedance profile in the impactor. Previously inaccessible thermodynamic states beyond the quasi-isentropes and Hugoniot can now be reached in dynamic experiments with these impactors. In the light gas-gun experiments on copper reported here, we recorded the particle velocities of the Cu-LiF interfaces and employed hydrodynamic simulations to relate them to the thermodynamic phase diagram. Peak pressures for these experiments were on the order of megabars, and the time-scales ranged from nanoseconds to several microseconds. The strain rates of the quasi-isentropic experiments are approximately 10{sup 4} s{sup -1} to 10{sup 6} s{sup -1} in samples with thicknesses up to 5 mm. Though developed at a light-gas gun facility, such shaped pressure-profiles are also feasible in principle with laser ablation or magnetic driven compression techniques allowing for new directions to be taken in high pressure physics.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 898044
- Report Number(s):
- UCRL-JRNL-216464; TRN: US200706%%218
- Journal Information:
- Journal of Applied Physics, N/A, no. 2, July 15, 2006, pp. 023508, Journal Name: Journal of Applied Physics, N/A, no. 2, July 15, 2006, pp. 023508
- Country of Publication:
- United States
- Language:
- English
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