A Ripple Microstructure Formation on a Uniform-melted Material Surface by Nanosecond Laser Pulses

By a linear polarized nanosecond pulse laser, a ripple structure on the uniformly melted brass surface is produced, which characteristic period approximates to the wavelength of the ionic sonic wave. These features can be interpreted as the interaction between the laser-generated plasma (gas-phase) and the melted brass (liquid-phase). According to our model and the Lagrangian hydrodynamic algorithm simulation, the wavelength of the ionic sonic wave is calculated, which is in well agreement with our experiment observation.