Comparison of plasma parameters and line emissions of laser-induced plasmas of an aluminum target using single and orthogonal double nanosecond/picosecond pulses

• A comparison of LIBS signal keeping constant the ablation fluence is performed.
• Emission of ps laser ablation is up to four-fold enlarged compared with ns pulses.
• Drilling ablation efficiency is 6 times larger with ps compared with ns pulses.
• LIBS sensitivity with ps pulse ablation is equivalent to that of ns double pulse configuration.

The emission of laser-induced plasma on aluminum targets in air was investigated with nanosecond- and picosecond-pulsed Nd:YAG laser emitting at the fundamental wavelength. Orthogonal double pulse in pre-ablation and reheating configurations was also performed where the picosecond laser was employed to ablate the target. Ablation fluences were kept fixed at 100 J cm− 2 regardless of the laser pulse duration. Time integrated emission spectroscopy was employed to determine the plasma emission; thus, picosecond laser ablation provided larger figures than the nanosecond one. The emission was further enhanced when double pulse schemes were used. This enhancement was analyzed as a function of interpulse delays. Electron density and temperature evolutions were determined from time delays of 150 ns after the ablation plasma onset. Results are discussed in terms of the ablation rate.