Non‐Extensive Plasma Sheath Dynamics: Effects of Negative Ions and Secondary Electron Emission

Abstract

ABSTRACT This paper investigates the influence of negative ions and secondary electron emission on plasma sheath formation and structure. The system consists of primary electrons following the non‐extensive distribution, negative ions described by the Maxwell–Boltzmann distribution, and secondary electrons and positive ions modeled as a cold fluid. Using the Sagdeev potential approach, a generalized Bohm criterion is derived for both extensive and non‐extensive regimes. The floating potential is determined through flux conservation at the wall, while the secondary electron density at the sheath edge is obtained under the quasi‐neutrality assumption. The results highlight the critical role of key parameters, including electronegativity , the secondary electron emission coefficient , the temperature ratio between primary electrons and negative ions, and the non‐extensivity parameter , in the formation and properties of the plasma sheath. An increase in , , and reduces the Bohm criterion and significantly modifies the floating potential , particularly in non‐extensive plasma with super‐extensive electrons . Conversely, is strongly affected by , , and in sub‐extensive plasma . Moreover, acts as a stabilizing factor by reducing sheath thickness and making the electric potential less negative, while high values of enhance the net charge density and secondary electron density .