Investigation of the spall strength of graphite using nano- and picosecond laser pulses

Spallation phenomena in graphite targets were investigated experimentally under nano- and picosecond shock-wave action at laser facilities "Kamerton-T" (GPI RAS) and PHELIX (GSI). In the range of strain rates of 1 to 10 μs−1 at the first time, data of dynamic tensile strength of the material were obtained. At maximal realized strain rate of 14 μs−1, the spall strength value 2.1 GPa has been achieved that is 64% of the theoretical ultimate tensile strength of the graphite. Spallation was observed not only on the backside of the target, but also on its front (irradiated) surface. The morphology of the front and rear surfaces of the targets was studied using the optical and scanning electron microscopy. The structure of the graphite in irradiated area on the facial side as well as in the spallation zone on the rear side of the target was investigated by Raman scattering method. A comparison of the dynamic strength of the graphite with the dynamic strength of a synthetic diamond is done.