Optimization of the composition of Al-Mg alloy films for laser-driven flyer

Abstract

Laser-driven flyer technology attracts tremendous interests owing to the advantage of generating high pressure shocks at a relative simple and low-cost way. However, low energy conversion efficiency between flyer and laser restricts the further application of this technology. To improve the energy conversion efficiency in a laser-driven flyer assembly, Al-Mg alloy films with three varied compositions were fabricated via magnetron sputtering. The composition, surface morphology, light absorption and thermal properties of the films were investigated using energy dispersive spectrometer, atomic force microscopy, ultraviolet–visible spectrophotometer and laser flash method. The reflectivity of the Al-Mg alloy film at 1064-nm wavelength decreases from 87.2% to 69.3% in comparison with Al film. Moreover, the thermal diffusivity of all the Al-Mg alloy films is lower than that of Al film and varies with the composition. The behavior of the plasma induced shock wave evolution was investigated by shadowgraph imaging technique, indicating that the spatial and temporal evolution of the shock wave agrees well with the form of a Taylor-Sedov spherical shock and the calculated shock wave energy of the Al-Mg alloy films can reach up to 1.19 times that of Al film. Furthermore, the ability to launch a 17-μm-thick Al flyer was characterized by a Photonic Doppler Velocimetry, and there is a 20.9% and 46.12% increase in the terminal velocity and energy conversion efficiency of the Al flyers for Al-Mg alloy films compared with Al film, respectively. Therefore, the performance of laser-driven flyer can be significantly improved by adjusting the composition of Al-Mg alloy films.