From a supersonic flow in a low pressure environment, nanoparticles were generated and the effects of corona discharge ions on the characteristics of the nanoparticles were investigated. The source material was silver, and a corona discharger was used as an ionizer to supply ions to the developed nanoparticle generator. Corona discharge ions provide nanoparticles with a repulsive electrical force that prevents aggregation of the particles. For a detailed analysis of the nanoparticle properties of size, morphology, composition, and charge, nanoparticles were investigated by means of transmission electron microscopy, an X-ray diffraction analysis, energy-dispersive spectroscopy, and by a Faraday cup current measurement. From a numerical calculation approach, the effects of the ions were predicted in terms of the formation and growth of the nanoparticles. Upon application of the corona discharge ions, the mean diameter and standard deviation of the generated nanoparticles were found to decrease. In addition, charged nanoparticles could be generated and the aggregation of particles decreased relatively. (c) 2007 Elsevier B.V. All rights reserved.