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 H2 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 H2 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.

Numerical solutions of stationary multifluid equations are used to study the formation and properties of the magnetized sheath near the boundary of a dusty plasma. The impacts of the strength of the magnetic field, the dust and plasma number densities, and the electron temperature on the sheath structure and spatial distributions of various quantities are investigated. It is shown that for a given angle of incidence of the magnetic field, there is a threshold magnetic field intensity above which some kind of large regular inhomogeneities develop on the spatial profile of the dust particles. The sheath thickness, the electron and ion number densities, and the absolute dust charge are strongly affected by the variation in the dust number density. The sheath demonstrates a nonlinear dependence on the electron temperature; as the electron temperature rises, the sheath first is broadened and the absolute wall potential decreases but then at higher temperatures the sheath becomes narrower and the absolute wall potential increases.

The effects of the electron energy distribution function (EEDF) on the structure of a dusty plasma sheath are investigated. Here, it is assumed that the electrons obey a Druyvesteyn-type distribution with a parameter $x$ controlling the shape of the EEDF. The Druyvesteyn-like distribution tends to a Maxwellian distribution as  $x$ varies from 2 to 1. Using the orbital motion limited theory, the incident electron current on the dust is evaluated for a given $x$ . The results of numerical simulations are compared with those of a Maxwellian distribution. It was found that the sheath dynamics depends strongly on the magnitude of $x$ . The sheath thickness increases monotonically with increasing $x$ . However, the absolute dust charge decreases and, as a result, the accelerating ion drag force is weakened and thus the dust number density is enhanced. For a plasma with a Druyvesteyn-like distribution, the Bohm speed is a function of $x$ and increases with increasing $x$ .

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