Statistical mechanics of dust charging in a multi-ion plasma with negative and positive ionic species

On the basis of statistical mechanics and charging kinetics, the charge distribution over uniform size spherical dust particles in a multi-ion plasma comprising of multiple charged negative and positive ions is investigated. Two specific situations where the complex plasma is viz., (i) dark (no emission from dust) and (ii) irradiated by laser light (causing photoemission from dust) have been taken into account. The analytical formulation includes the population balance equation for the charged dust particles along with number and energy balance of the complex plasma constituents. The departure of the results for multi-ion plasma from that in case of usual singly charged positive ion plasma is graphically illustrated and discussed. In contrast to electron-ion plasma, significant number of particles is seen to acquire opposite charge in case of pure positive-negative ion plasma, even in the absence of electron emission from the dust grains. The effects of various plasma parameters viz., number density, particle size, and work function of dust on charge distribution have also been examined