Index of refraction of shock-compressed fused silica and sapphire

Abstract

Explicit relations between index of refraction and density are obtained for shock-compressed fused silica and sapphire. The relations are derived from the Doppler-frequency corrections to velocity-interferometry data obtained by Barker and Hollenbach in plate-impact experiments. The index-density relation for sapphire was found using an expression for the Doppler-frequency shift produced by a window material experiencing shock compression. For fused silica, a numerical calculation was required to compute frequency corrections for the combined ramp/shock waveforms produced in the experiments. In both cases the behavior of the refractive index over the density range of the data was found to be predicted quite accurately by adding a correction term to the Gladstone-Dale relation. A particular power-law dependence on density was found for this correction term in each case. The explicit index-density relations permit detailed calculations to be made for index-of-refraction effects from window materials in plate-impact experiments using velocity interferometry. As an example, refractive-index effects are calculated for a fused silica window experiencing a slowly rising compression wave generated in a glass-ceramic material. The present results also permit the polarizability behavior of these materials under shock compression to be examined.

Shock Response of Diamond Crystals

“…Ancillary measurements using trigger pins and/or shock break out fibers would be made for both configurations. Furthermore, within the uncertainty induced by repeatability of projectile velocity in these shot pairs, an approximately VISAR window calibration factor [2][3][4][5] for diamond could be obtained under this scheme, yielding information about the refractive index under shock compression. An experimental campaign utilizing this configuration was to begin in Q4 of FY 01.…”

“…These window materials span a narrow range of shock impedances and usable pressures. Sapphire provides the highest shock impedance, but is limited to pressures below approximately 200 kbar [3,4]. LiF can be used to pressures approaching 2 Mbar, however it exhibits a relatively low shock impedance [2].…”

“…These materials include lithium fluoride (LiF) [2], sapphire [3,4], fused silica [3,4], PMMA [3], and z-cut quartz [5]. These window materials span a narrow range of shock impedances and usable pressures.…”

Pressure Effects on the Optical Properties of LuVO₄:Eu³⁺ Nanoparticles

“…There is no single opinion on the affect of high pressure on refractive index. Some authors take into account only molecular volume pressure dependence [32]. On the other hand some authors concluded that a change in polarizability is results only of the screening effects [33].…”

Line-imaging velocimeter for shock diagnostics at the OMEGA laser facility

“…Correction terms have been empirically determined for several windows including fused silica [16,37], LiF [38], sapphire [16,37], alpha quartz [39] and PMMA [16].…”