Nucleation in plasma: Catalyst nucleation rate in plasma systems used for production of nanoparticles

Abstract

According to the classic theory of nucleation around a charged particle, dipoles induced in the particle's neighbors by the charged nucleation center decrease the electric field around it. This reduces the system's Gibbs energy and thus increases the nucleation rate. Unlike the situation of a neutral gas and an already existing charged particle, in plasma, charging the center of nucleation is the result of the separation of charges (a negatively charged center and a positively charged surrounding). This process being similar to charging of a capacitor, it demands extra energy, and thus increases the Gibbs energy. As a result, the nucleation rate decreases in comparison with the nucleation rate in a neutral medium. In this work, the process of nucleation in a plasma is considered and the nucleation rate is calculated. It is shown that for the conditions typical for arcs used for the production of nanoparticles, the reduction in the nucleation rate is an order of magnitude or higher.