3-DIMENSIONAL MODELLING OF AIR FLOW AND NANO- AND MICRO-PARTICLE BEAM FOCOUSING IN AN INTEGRATED AERODYNAMIC LENSES

In this research a 3-dimensional numerical simulation of the airflow and nano- and micro-particle motions in an aerodynamic particle beam focusing system consisting of several lenses, nozzle and the chamber downstream of the nozzle was done. The 3-dimentional compressible airflow and thermal conditions in the aerodynamic lens system were evaluated. The governing equations of the particle motion are solved in a Lagrangian view. The particle equation of motion used included drag, and Brownian and gravity forces. The simulation results were compared with the experimental data. The results showed that for particle diameters less than 30 nm, the Brownian force could significantly affect the beam focusing and particle collection efficiency. Afterward the motion of the nano-particles in this range is 3-dimensional and the assumption of the axi-symmetric particle motions is not valid. The gravity effect, however, was found to be negligibly small and could be neglected in the analysis of nano-particle motions.