Observation of the partial reheating of the metallic vapor during the wire explosion process for nanoparticle synthesis

In this paper, an experimental study using time resolved imaging was reported to study the expansion of the vapor as well as subsequent formation of the arc plasma during the synthesis of Cu nanoparticles by wire explosion process to understand the influences of arc plasma formation on the characteristics of the produced nanoparticles by means of partial reheating of the vapor. Arc plasma is known to form after a delay or immediately depending on the ambience and pressure when the supplied energy is sufficient to sustain the plasma. Observations of two expanding concentric cylinders one inside another by time resolved imaging in the case of delayed formation of arc plasma suggest that the vapor of the wire material is expanding in front of the expansion of the arc plasma. Due to the expansion of the vapor in front of the arc plasma, some of the wire material may not be reheated by arc plasma as opposed to the case of immediate formation of arc plasma, where the vapor is expected to be reheated completely. Thus, the arc plasma formation has strong influence on the characteristics of the produced nanoparticles in wire explosion process and most probably explains the earlier reported opposite trends observed for particle size with varying pressure for different gases. (C) 2014 AIP Publishing LLC.