Effect of particle trapping in a three-component plasma sheath model containing Tsallis distributed electrons

Abstract

In this paper, the effect of particle trapping in a three-component plasma sheath model has been investigated analytically. The behavior of plasma sheath is studied with cold fluid ions, trapped/vortex-like hot electrons and cold q-nonextensive electrons. The trapped hot electrons follow Schamel’s vortex-like distribution. A modified Bohm sheath criterion and a sheath width equation have been analytically derived. It is seen that the thickness of the sheath explicitly depends on q-nonextensivity parameter, Bohm velocity, cold electron fraction, temperature and densities of cold and hot electrons; while the Bohm velocity depends on nonextensive parameter, fraction of cold electrons, temperature and densities of cold and hot electrons. It is observed that as the electron nonextensivity as well as fraction of cold electron increases, the Bohm velocity decreases and also the sheath width decreases. As the ratio between hot electrons temperature to cold electrons temperature increases, the Bohm velocity increases and the sheath thickness also increases. The increasing values of the ratio of cold electrons to hot electrons concentration results in the decrease of sheath width.