The effects of gas dilution on the nanoparticles nucleation in a low pressure capacitively coupled acetylene discharge

The effects of gas dilution on the chemistry of macromolecules and nucleation of nanoparticles in a low pressure radio-frequency acetylene discharge are investigated by employing a self-consistent, one dimensional multi-fluid model. Ar, He, and H-2 are used for the dilution with different percentages, keeping the total gas inlet constant. The results of numerical simulations showed that the nucleation rate decreases monotonically with H-2 fraction, when the plasma is diluted in hydrogen. But, for Ar and He diluted plasmas, the nucleation increases with increasing of the dilution up to 40%, and then declines. Diluting acetylene in Ar increases the electron number density and consequently the rate of electron impact hydrocarbon dissociation, the latter in turn leads to a more effective polymerization and nanoparticle nucleation. Radicals are identified as the most important species during the nucleation process and their number density is always higher in Ar diluted plasma than the other two. Published by AIP Publishing.