Mean charge  ⟨ Z ⟩  of dust agglomerates and the standard deviation as a function of the number of constituent monomers N (left panel). The upper abscissa relates N to the characteristic radius a_c of the BCCA agglomerate. The electron fraction x_e, the ion concentration x_i (with M⁺ as the dominant ion) and the mean charge of the dust  ⟨ Z ⟩  per dust agglomerate are shown at the right panel using solid, dashed, and dotted lines. The profiles shown are obtained at R = 10   AU and z/h_g = 0 applying the “reduced” network of the modified Oppenheimer-Dalgarno model with adsorption and desorption process switched off. D_BCCA = 2. The lines correspond to the values obtained by numerical integration while the values marked by (blue) filled circles are obtained using the semi-analytical solution.