The formation and propagation of laser-driven shock waves has been observed by optical
shadowgraphy in fused quartz, α-quartz and sodium chloride. Target materials were irradiated with a 0.53 µm , ~ 2.5 ns FWHM laser pulse at intensities ranging between
0.2 — 2 x 10¹³ W/cm², producing peak pressures varying from 0.3 — 3 Mbar at the shock front. Observations in both varieties of quartz reveal transient, high-speed shock propagation followed by deceleration towards a steady asymptotic shock speed. Similar high-speed transients were not seen in sodium chloride. The results in quartz were found to be in significant disagreement with both one-dimensional and two-dimensional hydrodynamic
calculations based on equilibrium equations of state. The non-steady shock propagation is interpreted as being due to a relaxation process in the phase transformation
of quartz into the high-pressure stishovite phase which occurs at the shock front. The effects of such a relaxation process on the shock dynamics and shock compression process are considered for the case of a direct relaxation from quartz into stishovite, as well as for an indirect relaxation process in which the -transformation of quartz into stishovite is preceded by shock-induced amorphization of the quartz. It is shown that either scenario would result in higher shock speeds and less compressible shock states than those obtained under equilibrium conditions. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/28728 |
| Date | January 1990 |
| Creators | Waterman, Alfred James |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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