Shock-tube study of spallation phenomena at strong shock wave interaction with graphite surface

Flight safety during the motion of a descent spacecraft in the Earth's atmosphere primarily depends on the reliability of the heat-protective layer on its surface. Such layers typically consist of ablative carbon-based composite materials. This study of the ablation phenomenon is carried out from the point of view of the mechanical spallation of carbon microparticles from the graphite surface at a strong shock wave reflection from it. During the experiments, the emission of ablation products from the graphite surface behind the reflected shock wave was recorded including time profiles of the radiation and the time-integrated emission spectrum in the visible/infrared spectral range. Analysis of the obtained experimental data and theoretical estimations allow one to conclude that the main mechanism of the graphite surface ablation under the action of a strong shock wave is the mechanical spallation of carbon microparticles from the surface of the sample.