Laser simulation of hypervelocity impact into porous graphite

• Laser facilities can create craters similar to hypervelocity impacts. • A crater depends only on the pressure field exerted on the target surface. • Numerical simulations are performed to obtain these pressure fields. • A method is proposed to determine the impact equivalent to a given laser shock. • This method is validated numerically and experimentally. Laser-driven shocks offer a compelling alternative to traditional launchers for simulating hypervelocity impacts (HVI), especially for studying very small projectiles or extremely high velocities. This paper describes the mechanism of crater formation by laser shock and points out the similarities with real projectile impacts. The pressure fields generated by the two processes are compared by numerical simulation. A method for determining the parameters of the HVI equivalent to a given laser shock is detailed: the equivalent projectile size and velocity are determined by interpolation in a numerical database of HVI. To illustrate this method on a solid example, a laser shot was performed on a graphite target with a time profile of 100 ns, a focal spot diameter of 250 µm, and an energy of 40 J. Equivalent aluminum and polymer projectiles are determined step by step. The validity of the result is discussed by comparing crater shapes and pressure fields from numerical simulations and experimental impact data.