Nanocluster formation within the vapor plume, produced by nanosecond-laser ablation: Effect of initial density and pressure distributions

The condensation of vapor in the expanding plume produced by ns-laser ablation is discussed within the framework of the Zeldovich and Raizer theory of condensation. The spherical plume expansion is described by a numerical solution of the hydrodynamic equations by the cubic interpolated pseudo-particle (CIP) method. This permits us to analyze the role of initial distributions of density and pressure on the size distribution function of nanoclusters. For parabolic distributions (for the plume expansion into vacuum), calculations reproduce the same results as those obtained by particular solutions of gas-dynamic equations. When initial distributions deviate from the parabolic distributions. the size distribution function varies. For the rectangular plume, the size distribution function of nanoclusters demonstrates two maximums. A similar effect is observed due to the ambient gas influence.