Study of the interplay of vaporisation, melt displacement and melt ejection mechanisms under multiple pulse irradiation of metals

A threefold study combining profilometry, high speed imaging and recoil momentum measurements is used to deconvolve the relative contributions to material removal attributable to vaporisation, melt displacement and explosive melt ejection. The interplay of these three mechanisms is studied as a function of the number of laser pulses incident on an aluminium target and pulse repetition frequency. This study shows cumulative heating affects matter removed as both vapour and liquid melt, and highlights the influence of the vapour plume and ablation crater morphology on the proportions of material removed as melt displacement and melt ejection.