Shock sapphire

L.M. Barker and R.E. Hollenbach, Shock-Wave Studies of PMMA, Fused Silica, and Sapphire, J. Appl. Phys. 41, 4208 (1970). 

The PVFj gauge has been calibrated up to 4 GPa (Bauer, 1984) for both shock loading and release. Graham and Lee (1986) have extended these calibration studies to about 20 GPa, and have measured both a shock loading and release profile in sapphire at 12 GPa, as indicated in Fig. 3.15. 

This loss of shear strength was confirmed as typical of other strong solids in mechanical response studies of shock-compressed sapphire by Graham and Brooks [71G01]. In this ease there was a substantial reduction, but not... 

Fig. 2.9. The measured stress-volume relation of shock-loaded sapphire reveals a substantial reduction in strength, but a small finite strength is retained. The reduction in strength is indicated by the small high pressure offset between the static and shock data, and from extrapolation of high pressure shock data to atmospheric pressure conditions (Graham and Brooks [71G01]).

Fig. 5.5. The electrical response of piezoelectric polymers under shock loading is studied experimentally by placing the thin PVDF element on the impact surface of a standard target, either the polymer, Kel F, z-cut quartz, or z-cut sapphire. The im-pactor is typically of the same material. The current pulse is recorded on transient digitizers with frequency responses from 250 to 1000 MHz.

Do not quench tubes, thermal or pressure shock will stress the sapphire and may lead to catastrophic failure. 

In the experiments described here, two separate techniques have been used for interferometric characterization of the shocked material s motion frequency domain interferometry (FDI) [69, 80-81] and ultrafast 2-d spatial interferometric microscopy [82-83]. Frequency domain interferometry was used predominantly in our early experiments designed to measure free surface velocity rise times [70-71]. The present workhorse in the chemical reaction studies presented below is ultrafast interferometric microscopy [82], This method can be schematically represented as in Figure 6. A portion of the 800 nm compressed spectrally-modified pulse from the seeded, chirped pulse amplified Ti sapphire laser system (Spectra Physics) was used to perform interferometry. The remainder of this compressed pulse drives the optical parametric amplifier used to generate tunable fs infrared pulses (see below). 

R. A. Graham and W. P. Brooks, Shock-wave compression of sapphire from 15 to 420kbar, J. Phys. Chem. Sol. 1971, 32, 2311-2330. 

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