Dynamic Fracture of Borosilicate Glass with Plasma Confinement geometry in Pure Water by Laser-induced Shock Wave

In order to characterize dynamic fracture of borosilicate glass, we performed laser-shock-experiments of both an aluminum-ablator mounted glass and a glass with plasma confinement geometry in pure water by Q-switched Nd$^{3+}$:YAG laser. The incident beam with 440 mJ were focused onto the target approximately 300 $\mu $m in diameter. The dynamic fracture of the glass targets is observed with high-speed digital framing-camera photography. For the aluminum-ablator mounted glass, propagation of the shock wave in water was observed, and the shock-wave velocity is obtained to be 1.65 $\pm$ 0.02 km/s using image processing. Shock-pressure applied the target is estimated to be 180 MPa by Hugoniot relation. For the glass with plasma confinement geometry, generation of the micro-fragments from the rear side of the target was observed. This result indicates that shock-induced fragmentation by laser irradiation is enhanced by the plasma confinement effect. The soft-recovered fragments are separated according the size with PET mesh having deferent mesh size. As a result, the glass with plasma confinement geometry generated smaller fragment than the aluminum-ablator mounted glass.