The synthesis of silver nanoparticles by a supersonic nozzle expansion method with corona discharge ions was investigated. For supplying ions in the developed nanoparticles generator, a corona discharger was used as an ionizer. Corona discharge ions function as nuclei for heterogeneous nucleation in the silver nanoparticle formation process and provide silver nanoparticles with a repulsive electrical force that prevents aggregation of the particles. For detailed analysis of such properties of synthesized nanoparticles as size, morphology, composition, and charge, sampled nanoparticles were investigated by means of transmission electron microscopy, x-ray diffraction analysis, energy-dispersive spectroscopy, and Faraday cup current measurement. Upon application of the corona discharge ions, the mean diameter of the synthesized nanoparticles was found to decrease. Further, charged and nonagglomerated silver nanoparticles can be synthesized. (c) 2007 American Vacuum Society.