Listening to laser sparks: a link between Laser-Induced Breakdown Spectroscopy, acoustic measurements and crater morphology

Highlights: • The shot-to-shot LIBS acoustic signal decrease is lower as the target is denser. • Acoustic energy can be used as a remote tracer of the ablated volume. • Acoustics give information about the ablation that is independent from LIBS spectra. -- Abstract: In preparation for the SuperCam/Mars Microphone scientific investigation, the acoustic signal associated with the plasma formation during Laser-Induced Breakdown Spectroscopy (LIBS) experiment is studied with regard to the shot-to-shot evolution of the laser induced crater morphology and plasma emission lines. A set of geological targets are depth profiled using a specifically designed LIBS setup coupled with acoustic test bench under ambient terrestrial atmosphere. Experiments confirm that the decrease of the acoustic energy as a function of the number of shots is well correlated with the target hardness/density and also demonstrate that the acoustic energy can be used as a remote tracer of the ablated volume of the target. Listening to LIBS sparks provides a new information relative to the ablation process that is independent from the LIBS spectrum.