Projectile acceleration to a velocity over the Earth's escape velocity and application in planetary science.

Impact velocity of meteorites on Earth at the final stage of planetary accretion becomes more than 10 km/s. However, macroscopic (larger than 0.1 mm) projectiles are not easily accelerated to more than 10 km/s by two-stage light-gas guns. One possible method to a velocity larger than 10 km/s is the irradiation of high-intensity lasers. Here, we describe the first results of projectile (glass spheres) acceleration experiments to a velocity higher than 10 km/s using GEKKO XII laser at Institute of Laser Engineering. Glass spheres are accelerated to a velocity of 15 km/s. This is enough to simulate hypervelocity impacts on the surface of the proto-planets and investigate various phenomena caused by the impacts such as impact vaporization of silicate rocks, crater formation on rocks, and metamorphism due to high pressure.