Quantum effects in electron emission from and accretion on negatively charged spherical particles in a complex plasma

Abstract

The authors have investigated the electron emissions (thermionic, electric field, photoelectric, and light induced field) from and electron accretion on a charged particle in a complex plasma, on the basis of a three region electrical potential model in and around a charged spherical particle in a complex plasma, characterized by Debye shielding. A continuous variation of the transmission coefficient across the surface of a particle (corresponding to emission and accretion) with the radial electron energy ɛr has been obtained. It is seen that the numerical values of the emission and accretion transmission coefficients [D(ɛr)] are almost the same. This is the necessary and sufficient condition for the validity of Saha’s equation for thermal equilibrium of a system of dust and electrons. This is in contrast to the earlier condition, which limited the range of validity of Saha’s equation to the range of the applicability of Born approximation. It is seen that D(ɛr) increases with increasing ɛr, increasing negative electric potential on the surface, decreasing radius, and deceasing Debye length. The electron currents, corresponding to thermionic, electric field, photoelectric and light induced field emission increase with increasing surface potential; this fact may have significant repercussions in complex plasma kinetics. Since numerically D(ɛr) is significantly different from unity in the range of ɛr of interest, it is necessary to take into account the D(ɛr)−ɛr dependence in complex plasma theory.