Laser matter interaction; Microstructures and defects; Confinement geometry target; Glass transmission; Free electron density;FEMTOSECOND LASER; TRANSPARENT SOLIDS; INDUCED PLASMA; SHOCK-WAVES; LINES; ABLATION; SURFACE; TEMPERATURE; DIAGNOSTICS; DEPENDENCE

Confinement geometry target assemblies are very important in the study of laser shocked materials. The shock pressure in confinement geometry depends on incident laser intensity and has main limitation of dielectric breakdown of transparent materials used for confinement. This makes study of damage mechanism induced by laser pulses in dielectric materials necessary. We investigated the front and rear surface damage threshold of borosilicate glass (dielectric material) and their dependency on laser parameters. The induced damage width, geometries and microstructure changes are analyzed with optical microscope, scanning electron microscope and Raman spectroscopy. The results show that at low energies symmetrical damages are found and these damage width increases nonlinearly with laser intensity. The emitted optical spectrum during the process of breakdown is also investigated and is used for the characterization of emitted plasma such as plasma temperature and free electron density. Optical emission lines from Si I, Si II and Si III ions are used for temperature and density estimations. The plasma temperature and density are measured as similar to 0.94 eV and 10(16)-10(17) cm(-3) respectively. All results are found consistent with the earlier, published results and are used in designing the confinement geometry targets for laser shock experiments. (C) 2017 Published by Elsevier B.V.