Nonextensive Statistical Mechanics and its Effect on the Electronegative Plasma Sheath Characteristics

In recent years, a great deal of consideration has been paid to the nonextensivegeneralization of the Boltzmann-Gibbs-Shannon (BGS) entropy where it has been successfullyused to explain some interesting problems in physics. Self-gravitating systems and plasma aretwo main candidates that use this entropy [1-3]. This entropy first recognized by Renyi [4] andthen proposed by Tsallis [5]. Tsallis proposed the q-entropy as (...), where K(B)is the Boltzmann constant, P(i)is the probability of the i’th microstate and q is a parameterquantifying the degree of non-extensivity of the system. In this work, using multi fluid modeland Sagdeev potential method, a modified Bohm’s criterion for formed sheath in collisionalelectronegative plasma in which electrons and negative ions have non-extensive velocitydistribution, is derived. The effects of nonextensivity degree q and collision parameter σ on theformed sheath criterion which has upper and lower limits are investigated. Furthermore themodified Bohm’s criterion which we obtain coincides with those given by the Maxwellaindistribution function, when q tends to 1. Also by using numerical methods the behavior ofpositive ions density and electrical potential in the sheath region for different value of q and σ asfunction of normalized distance are studied.

کلیدواژه ها:

Nonextensive Statistical Mechanics ، Plasma Sheath