Sheath structure behavior in collisional non-extensive plasma with negative ions

Abstract

The present paper numerically investigates the sheath structure in a collisional electronegative plasma in the presence of non-zero ion source term. The plasma sheath contains non-extensively distributed electrons, fluid positive ions with finite temperature, and Boltzmann-distributed negative ions. Using the Sagdeev potential method, a modified Bohm sheath criterion is derived to obtain the ion velocity at the sheath entrance that satisfies the sheath formation condition. The impact of the main parameters like electronegativity D, non-extensivity q, ionization frequency $\updelta$ and collision frequency ${\alpha }$ on the sheath characteristics has been examined. The requirement of positive ion velocity to enter the sheath is found to decrease with the increment of ${\alpha }$ and $\updelta$. Moreover, it is seen that as q, D, $\updelta$ and ${\alpha }$ increase, the normalized electric potential rapidly rises, the peak amplitude of the space charge density increases, and the sheath thickness significantly decreases. Furthermore, as D decreases, the effect of q, $\updelta$ and ${\alpha }$ on the sheath electric potential and the space charge density becomes more important. This study may be useful in various technological applications, including plasma-based surface treatments, plasma etching, and plasma cleaning. This is particularly relevant in the microelectronic and semiconductor industries for manufacturing electronic devices and integrated circuits. Additionally, it could contribute to the enhancement and advancement of techniques in fusion energy research.