Electronegative plasma sheath is addressed in a collisional unmagnetized plasma consisting of q-nonextensive electrons, Boltzmann distributed negative ions and cold fluid positive ions. Considering the positive ion-neutral collisions and ignoring the effects of ionization and collisions between negative species and positive ions (neutrals), a modified Bohm sheath criterion and hence floating potential are derived by using multifluid model. Using the modified Bohm sheath criterion, the sheath characteristics such as spatial profiles of density, potential and net space charge density have been numerically investigated. It is found that increasing values of q-nonextensivity, electronegativity and collisionality lead to a decrease of the sheath thickness and an increase of the sheath potential and the net space charge density. With increasing values of the electron temperature to negative ion temperature ratio, the sheath thickness increases and the sheath potential as well as the net space charge density in the sheath region decreases.
This paper presents the behavior of plasma profiles of a sheath in unmagnetized collisionless plasma in the presence of nonextensively distributed two-temperature electrons and isothermal ions. A theoretical model is developed where isothermal ions are described by the conventional hydrodynamic equations along with the effect of electron nonextensivity described by q-distribution function. The plasma sheath parameters like Bohm velocity, potential, and density profiles in the presence of nonextensively distributed two-temperature electrons and isothermal ions are investigated.
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