Cluster formation in copper vapor jet expanding into vacuum: the direct simulation Monte Carlo

• Published in: Vacuum Vol. 163; pp. 119 - 127
• Main Authors: Bykov, N.Y., Gorbachev, Yu.E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2019
• Subjects: Condensation; Cu clusters; Direct simulation Monte Carlo; Expansion into vacuum; Nanoclusters; Rarefied jet; Direct simulation Monte Carlo; Expansion into vacuum; Condensation; Rarefied jet; Cu clusters; Nanoclusters
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2019.02.007

Expansion of the condensing copper vapor into vacuum from a high-temperature source is studied for transient and near-continuum flow regimes within the direct simulation Monte Carlo method. Kinetic approach, which assumes cluster formation/decay description via monomer-cluster reactions with corresponding cross-sections, is employed. Clusters observed in calculations are of subnanoscale size. Impact of condensation on gas-dynamic jet parameters is significant for the regimes for which the terminal mole cluster fraction in the jet exceeds 1%. For such regimes both velocities and translation temperatures of clusters and monomers, are close to each other, while cluster internal temperature is higher than the translational vapor temperature. Characteristic clusterization modes are revealed depending on the intensity of the cluster formation process in the source domain and in the jet. Obtained values of the internal dimer temperature and average cluster size in the jet far field are in a good agreement with the experimental data and known scaling laws. •Subnanoscale clusters form in rarefied copper vapor flow expanding into vacuum.•Cluster formation process is simulated by the kinetic approach within DSMC.•Condensation affects flow parameters for Knudsen numbers less than 0.01•Non-equilibrium effects due to energy release and flow rarefaction.