A simple nozzle configuration for the production of low divergence supersonic cluster beam by aerodynamic focusing

A nozzle configuration for the production of an intense and collimated supersonic cluster beam is presented and characterized by numerical modeling. A simple lens added to a cylindrical nozzle exploits aerodynamic focusing effects. The effect of the focalizing nozzle is an enrichment of the core of the jet with clusters of an arbitrary size interval depending on carrier gas pressure and temperature. The influence of the source and nozzle geometrical parameters and of the expansion conditions on the cluster focalization is simulated and compared to the experimental results. A collimating effect on particle velocities and the possibility of obtaining a cluster mass selection is also observed.