IMPACT EXPERIMENTS WITH PROJECTILES AT VELOCITIES HIGHER THAN 10 KM/S.

Impact velocity of meteorites on planetary and satellite surfaces at the final stage of planetary accretion becomes more than 10 km/s. The impacts with velocities higher than 10 km/s generate very large craters and a large amount of silicate vapor, melt, and fast ejecta, and would make great effects on the planetary surface environments. However, the details of the effects by such impacts on the environments have not been understood well yet. The reasons are probably that macroscopic (>∼0.1 mm) projectiles are not easily accelerated to more than 10 km/s in laboratories. This makes it difficult to investigate experimentally the impact phenomenon with impact velocities higher than 10 km/s. In this paper, we demonstrate that higher impact velocities than 10 km/s can be achieved using projectiles with a diameter of 0.1–0.3 mm: we accelerate glass and aluminum projectiles using a high-power laser, GEKKO XII—HIPER. The projectiles are collided into LiF targets. We observe some lines of Li gas using a time-resolved spectrometer after an estimated impact time, which indicates that the impact vaporization with higher velocities than 10 km/s occurs. [ABSTRACT FROM AUTHOR]