Abstract
Conventional shock wave experiments need interferometric windows in order to determine the equation of state of a large variety of metals. Lithium fluoride (LiF) and sapphire are extensively used for that purpose because their optical transparencies enable the optical diagnostics at interfaces under a given range of shock pressure. In order to simulate and analyse the experiments it is necessary to gather a correct knowledge of the optical and mechanical properties of these windows. Therefore, our window supplies are systematically characterized and an experimental campaign under shock loading is conducted. Our preliminary work on LiF windows at 532 nm is in good agreement with literature data at room temperature and the new characterization at 450 K enables a better interpretation of our preheated target experiments. It confirms the predominant effect of density on optical properties under pressure and temperature. The present work demonstrates that the initial density determination is a key point and that the uncertainties need to be improved. For that purpose, complementary experiments are conducted on LiF windows with simplified target designs and enriched diagnostics, coupling VISAR (532 nm) and PdV (1550 nm) diagnostics. Furthermore, a similar campaign is conducted on sapphire windows with symmetric impact configuration.
Highlights
Conventional shock wave experiments need interferometric windows in order to determine the equation of state of a large variety of metals
The uncertainties are 3% for the shock pressure and 2% for the density. These results serve some remarks to emphasize that the initial density is a crucial parameter for the Lithium fluoride (LiF) characterization
This new campaign conducted on LiF windows at 1550 nm with a PDV diagnostic is in good agreement with literature data at ambient temperature
Summary
Traditional shock wave experiments need windows to characterize a variety of materials. Lithium fluoride (LiF) along [100] axis is extensively used for that purpose because it remains optically transparent until more than 100 GPa. In order to analyse and simulate the experiments it is necessary to have a good knowledge of the optical and mechanical properties of these LiF windows. In order to analyse and simulate the experiments it is necessary to have a good knowledge of the optical and mechanical properties of these LiF windows This in mind it is necessary to characterize our windows supply: density, crystalline orientation, acoustic velocity and geometrical measurements. A preliminary campaign [1] was conducted in order to characterize the behaviour under dynamic loading in particular at 450 K which is the selected temperature level for our preheated system [2]. The present work presents a simplified target configuration with a PDV diagnostic (1550 nm)
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