Sheath structure in plasmas with nonextensively distributed electrons and thermal ions

Sheath region of an electropositive plasma consisting of q-nonextensive electrons and singly charged positive ions with finite temperature is modeled. Using Sagdeev's pseudo potential technique to derive the modified sheath formation criterion, it is shown that the velocity of ions at the sheath edge is directly proportional to the ion temperatures and inversely proportional to the degree of nonextensivity of electrons (q-parameter). Using the modified Bohm criterion, effect of degree of nonextensivity of electrons and temperature of positive ions on the characteristics of the sheath region are investigated numerically. It is shown that an increase in the ion temperature gives rise to an increase in the electrostatic potential and the velocity of ions in the sheath regardless of the value of q. Furthermore, it is seen that the sheath width and the density distribution of the charged particles decrease by increasing the temperature of positive ions. In addition, it is found that the positive ion temperature is less effective on the sheath structure for higher values of the q-parameter. Finally, the results obtained for a thermal plasma with nonextensively distributed electrons are compared with the results of a cold plasma with nonextensive electrons and an extensive (Maxwellian) plasma with thermal ions.