In this paper, a plasma sheath containing primary electrons, cold positive ions, and secondary electrons is studied using a one-dimensional fluid model in which the primary electrons are described by q-non-extensive distribution according to the Tsallis statistics. Based on the Sagdeev potential method and the current balance relation, a modified sheath criterion, and floating potential are established theoretically. The effect of secondary electron emission on q-non-extensive plasma sheath characteristics have been numerically examined. A significant change is observed in the quantities characterizing the non-extensive plasma sheath with the presence of the secondary electrons. It is found that the sheath properties with super-extensive distribution (q < 1) and sub-extensive distribution (q > 1) are different compared with plasma sheath with Maxwell distribution (q = 1).

This paper investigates the influence of the driving frequency on the dynamics of a single dust particle in argon radiofrequency discharge. A one-dimensional fluid model is presented and solved in the entire inter-electrode domain using the finite difference method. In order to solve the particle equation of motion, the coefficients describing the amplification and the damping of the dust particle oscillations are analytically calculated around the equilibrium position, these coefficients allow us to find the relation between the plasma and dust parameters. The results obtained cover the discharge characteristics, the charge and the dynamics of the dust particle. It has been found that the driving frequency has a significant effect on not only the discharge properties but also on the damped oscillatory motion and the equilibrium position of the dust particle. Hence, these oscillations become closer to the electrodes with increasing driving frequency whereas the dust equilibrium position becomes relatively farther from the powered electrode when the dust size decreases.

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