Studies on condensation phenomena and refraction index distributions in excimer laser-induced plasma/vapour plumes

In this contribution, the condensation theory of I. M. Lifshitz and V. V. Slyozov is used to calculate the formation of metal clusters in the plasma/vapor regime above an aluminum target in a nitrogen atmosphere of 1 bar irradiated with 248 nm, 30 ns FWHM pulses. This theory takes into account formation of clusters by fluctuations in the supersaturated medium (plasma/vapor). It also accounts for both cluster growth due to atom-cluster-collisions (nucleation) and collisions between clusters (coalescence state). This condensation model is integrated in a gasdynamic code which calculates the flow field and the thermodynamic properties of the plasma/vapor. In addition, the density of electrons, clusters, and neutral particles are determined and, finally, with the appropriate polarizability the refraction index can be calculated. The theoretical data are discussed together with the results of interferometric measurements.